Temporal patterns of diversification across global cichlid biodiversity (Acanthomorpha: Cichlidae.

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Caleb D McMahan

Full Text Available The contrasting distribution of species diversity across the major lineages of cichlids makes them an ideal group for investigating macroevolutionary processes. In this study, we investigate whether different rates of diversification may explain the disparity in species richness across cichlid lineages globally. We present the most taxonomically robust time-calibrated hypothesis of cichlid evolutionary relationships to date. We then utilize this temporal framework to investigate whether both species-rich and depauperate lineages are associated with rapid shifts in diversification rates and if exceptional species richness can be explained by clade age alone. A single significant rapid rate shift increase is detected within the evolutionary history of the African subfamily Pseudocrenilabrinae, which includes the haplochromins of the East African Great Lakes. Several lineages from the subfamilies Pseudocrenilabrinae (Australotilapiini, Oreochromini and Cichlinae (Heroini exhibit exceptional species richness given their clade age, a net rate of diversification, and relative rates of extinction, indicating that clade age alone is not a sufficient explanation for their increased diversity. Our results indicate that the Neotropical Cichlinae includes lineages that have not experienced a significant rapid burst in diversification when compared to certain African lineages (rift lake. Neotropical cichlids have remained comparatively understudied with regard to macroevolutionary patterns relative to African lineages, and our results indicate that of Neotropical lineages, the tribe Heroini may have an elevated rate of diversification in contrast to other Neotropical cichlids. These findings provide insight into our understanding of the diversification patterns across taxonomically disparate lineages in this diverse clade of freshwater fishes and one of the most species-rich families of vertebrates.

Ancestral and derived attributes of the dlx gene repertoire, cluster structure and expression patterns in an African cichlid fish

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Renz Adina J

2011-01-01

Full Text Available Abstract Background Cichlid fishes have undergone rapid, expansive evolutionary radiations that are manifested in the diversification of their trophic morphologies, tooth patterning and coloration. Understanding the molecular mechanisms that underlie the cichlids' unique patterns of evolution requires a thorough examination of genes that pattern the neural crest, from which these diverse phenotypes are derived. Among those genes, the homeobox-containing Dlx gene family is of particular interest since it is involved in the patterning of the brain, jaws and teeth. Results In this study, we characterized the dlx genes of an African cichlid fish, Astatotilapia burtoni, to provide a baseline to later allow cross-species comparison within Cichlidae. We identified seven dlx paralogs (dlx1a, -2a, -4a, -3b, -4b, -5a and -6a, whose orthologies were validated with molecular phylogenetic trees. The intergenic regions of three dlx gene clusters (dlx1a-2a, dlx3b-4b, and dlx5a-6a were amplified with long PCR. Intensive cross-species comparison revealed a number of conserved non-coding elements (CNEs that are shared with other percomorph fishes. This analysis highlighted additional lineage-specific gains/losses of CNEs in different teleost fish lineages and a novel CNE that had previously not been identified. Our gene expression analyses revealed overlapping but distinct expression of dlx orthologs in the developing brain and pharyngeal arches. Notably, four of the seven A. burtoni dlx genes, dlx2a, dlx3b, dlx4a and dlx5a, were expressed in the developing pharyngeal teeth. Conclusion This comparative study of the dlx genes of A. burtoni has deepened our knowledge of the diversity of the Dlx gene family, in terms of gene repertoire, expression patterns and non-coding elements. We have identified possible cichlid lineage-specific changes, including losses of a subset of dlx expression domains in the pharyngeal teeth, which will be the targets of future functional

Temporal diversification of Central American cichlids

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Hulsey C Darrin

2010-09-01

Full Text Available Abstract Background Cichlid fishes are classic examples of adaptive radiation because of their putative tendency to explosively diversify after invading novel environments. To examine whether ecological opportunity increased diversification (speciation minus extinction early in a species-rich cichlid radiation, we determined if Heroine cichlids experienced a burst of diversification following their invasion of Central America. Results We first reconstructed the Heroine phylogeny and determined the basal node to use as the root of Central American Heroine diversification. We then examined the influence of incomplete taxon sampling on this group's diversification patterns. First, we added missing species randomly to the phylogeny and assessed deviations from a constant rate of lineage accumulation. Using a range of species numbers, we failed to recover significant deviations from a pure-birth process and found little support for an early burst of diversification. Then, we examined patterns of lineage accumulation as nodes were increasingly truncated. We assumed that as we removed more recently diverged lineages that sampling would become more complete thereby increasing the power to detect deviations from a pure-birth model. However, truncation of nodes provided even less support for an early burst of diversification. Conclusions Contrary to expectations, our analyses suggest Heroine cichlids did not undergo a burst of diversification when they invaded from South America. Throughout their history in Central America, Heroine cichlids appear to have diversified at a constant rate.

Embryonic and larval development in the Midas cichlid fish species flock (Amphilophus spp.): a new evo-devo model for the investigation of adaptive novelties and species differences.

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Kratochwil, Claudius F; Sefton, Maggie M; Meyer, Axel

2015-02-26

Central American crater lake cichlid fish of the Midas species complex (Amphilophus spp.) are a model system for sympatric speciation and fast ecological diversification and specialization. Midas cichlids have been intensively analyzed from an ecological and morphological perspective. Genomic resources such as transcriptomic and genomic data sets, and a high-quality draft genome are available now. Many ecologically relevant species-specific traits and differences such as pigmentation and cranial morphology arise during development. Detailed descriptions of the early development of the Midas cichlid in particular, will help to investigate the ontogeny of species differences and adaptations. We describe the embryonic and larval development of the crater lake cichlid, Amphilophus xiloaensis, until seven days after fertilization. Similar to previous studies on teleost development, we describe six periods of embryogenesis - the zygote, cleavage, blastula, gastrula, segmentation, and post-hatching period. Furthermore, we define homologous stages to well-described teleost models such as medaka and zebrafish, as well as other cichlid species such as the Nile tilapia and the South American cichlid Cichlasoma dimerus. Key morphological differences between the embryos of Midas cichlids and other teleosts are highlighted and discussed, including the presence of adhesive glands and different early chromatophore patterns, as well as variation in developmental timing. The developmental staging of the Midas cichlid will aid researchers in the comparative investigation of teleost ontogenies. It will facilitate comparative developmental biological studies of Neotropical and African cichlid fish in particular. In the past, the species flocks of the African Great Lakes have received the most attention from researchers, but some lineages of the 300-400 species of Central American lakes are fascinating model systems for adaptive radiation and rapid phenotypic evolution. The availability

Species-specific differences in adaptive phenotypic plasticity in an ecologically relevant trophic trait: hypertrophic lips in Midas cichlid fishes.

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Machado-Schiaffino, Gonzalo; Henning, Frederico; Meyer, Axel

2014-07-01

The spectacular species richness of cichlids and their diversity in morphology, coloration, and behavior have made them an ideal model for the study of speciation and adaptive evolution. Hypertrophic lips evolved repeatedly and independently in African and Neotropical cichlid radiations. Cichlids with hypertrophic lips forage predominantly in rocky crevices and it has been hypothesized that mechanical stress caused by friction could result in larger lips through phenotypic plasticity. To test the influence of the environment on the size and development of lips, we conducted a series of breeding and feeding experiments on Midas cichlids. Full-sibs of Amphilophus labiatus (thick-lipped) and Amphilophus citrinellus (thin-lipped) each were split into a control group which was fed food from the water column and a treatment group whose food was fixed to substrates. We found strong evidence for phenotypic plasticity on lip area in the thick-lipped species, but not in the thin-lipped species. Intermediate phenotypic values were observed in hybrids from thick- and thin-lipped species reared under "control" conditions. Thus, both a genetic, but also a phenotypic plastic component is involved in the development of hypertrophic lips in Neotropical cichlids. Moreover, species-specific adaptive phenotypic plasticity was found, suggesting that plasticity is selected for in recent thick-lipped species. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Lake Malawi cichlid evolution along a benthic/limnetic axis.

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Hulsey, C D; Roberts, R J; Loh, Y-H E; Rupp, M F; Streelman, J T

2013-07-01

Divergence along a benthic to limnetic habitat axis is ubiquitous in aquatic systems. However, this type of habitat divergence has largely been examined in low diversity, high latitude lake systems. In this study, we examined the importance of benthic and limnetic divergence within the incredibly species-rich radiation of Lake Malawi cichlid fishes. Using novel phylogenetic reconstructions, we provided a series of hypotheses regarding the evolutionary relationships among 24 benthic and limnetic species that suggests divergence along this axis has occurred multiple times within Lake Malawi cichlids. Because pectoral fin morphology is often associated with divergence along this habitat axis in other fish groups, we investigated divergence in pectoral fin muscles in these benthic and limnetic cichlid species. We showed that the eight pectoral fin muscles and fin area generally tended to evolve in a tightly correlated manner in the Lake Malawi cichlids. Additionally, we found that larger pectoral fin muscles are strongly associated with the independent evolution of the benthic feeding habit across this group of fish. Evolutionary specialization along a benthic/limnetic axis has occurred multiple times within this tropical lake radiation and has produced repeated convergent matching between exploitation of water column habitats and locomotory morphology.

A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids.

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McGee, Matthew D; Borstein, Samuel R; Neches, Russell Y; Buescher, Heinz H; Seehausen, Ole; Wainwright, Peter C

2015-11-27

Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion. Copyright © 2015, American Association for the Advancement of Science.

How many species of cichlid fishes are there in African lakes?

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Turner, G F; Seehausen, O; Knight, M E; Allender, C J; Robinson, R L

2001-03-01

The endemic cichlid fishes of Lakes Malawi, Tanganyika and Victoria are textbook examples of explosive speciation and adaptive radiation, and their study promises to yield important insights into these processes. Accurate estimates of species richness of lineages in these lakes, and elsewhere, will be a necessary prerequisite for a thorough comparative analysis of the intrinsic and extrinsic factors influencing rates of diversification. This review presents recent findings on the discoveries of new species and species flocks and critically appraises the relevant evidence on species richness from recent studies of polymorphism and assortative mating, generally using behavioural and molecular methods. Within the haplochromines, the most species-rich lineage, there are few reported cases of postzygotic isolation, and these are generally among allopatric taxa that are likely to have diverged a relatively long time in the past. However, many taxa, including many which occur sympatrically and do not interbreed in nature, produce viable, fertile hybrids. Prezygotic barriers are more important, and persist in laboratory conditions in which environmental factors have been controlled, indicating the primary importance of direct mate preferences. Studies to date indicate that estimates of alpha (within-site) diversity appear to be robust. Although within-species colour polymorphisms are common, these have been taken into account in previous estimates of species richness. However, overall estimates of species richness in Lakes Malawi and Victoria are heavily dependent on the assignation of species status to allopatric populations differing in male colour. Appropriate methods for testing the specific status of allopatric cichlid taxa are reviewed and preliminary results presented.

Genetic isolation and morphological divergence mediated by high-energy rapids in two cichlid genera from the lower Congo rapids

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Stiassny Melanie LJ

2010-05-01

Full Text Available Abstract Background It is hypothesized that one of the mechanisms promoting diversification in cichlid fishes in the African Great Lakes has been the well-documented pattern of philopatry along shoreline habitats leading to high levels of genetic isolation among populations. However lake habitats are not the only centers of cichlid biodiversity - certain African rivers also contain large numbers of narrowly endemic species. Patterns of isolation and divergence in these systems have tended to be overlooked and are not well understood. Results We examined genetic and morphological divergence among populations of two narrowly endemic cichlid species, Teleogramma depressum and Lamprologus tigripictilis, from a 100 km stretch of the lower Congo River using both nDNA microsatellites and mtDNA markers along with coordinate-based morphological techniques. In L. tigripictilis, the strongest genetic break was concordant with measurable phenotypic divergence but no morphological disjunction was detected for T. depressum despite significant differentiation at mtDNA and nDNA microsatellite markers. Conclusions The genetic markers revealed patterns of philopatry and estimates of genetic isolation that are among the highest reported for any African cichlid species over a comparable geographic scale. We hypothesize that the high levels of philopatry observed are generated and maintained by the extreme hydrology of the lower Congo River.

Algal dermatitis in cichlids.

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Yanong, Roy P E; Francis-Floyd, Ruth; Curtis, Eric; Klinger, Ruth Ellen; Cichra, Mary E; Berzins, Ilze K

2002-05-01

Three varieties of a popular African cichlid aquarium species, Pseudotropheus zebra, from 2 tropical fish farms in east central Florida were submitted for diagnostic evaluation because of the development of multifocal green lesions. The percentage of infected fish in these populations varied from 5 to 60%. Fish were otherwise clinically normal. Microscopic examination of fresh and fixed lesions confirmed algal dermatitis, with light invasion of several internal organs in each group. A different alga was identified from each farm. Fish from farm A were infected with Chlorochytrium spp, whereas fish from farm B were infected with Scenedesmus spp. Because of the numbers of fish involved, bath treatments to remove the algae from affected fish from farm B were attempted, with different dosages of several common algaecides including copper sulfate pentahydrate, diuron, and sodium chloride. However, none of these treatments were successful, possibly because of the location of the algae under the scales and within the dermis, and also because of the sequestering effect of the granulomatous response. To our knowledge, this is the first report of algal dermatitis in ornamental cichlids, as well as the first report of Scenedesmus spp infection in any fish.

New record of a fossil haplotilapiine cichlid from Central Kenya

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Stefanie B. R. Penk

2015-11-01

Full Text Available African freshwater cichlids (Cichlidae: Pseudocrenilabrinae are well known for their exceptionally great diversity and their capability of rapid speciation as well as diverse adaptations. The extant Pseudocrenilabrinae can be grouped into 27 tribes, with more than 2000 species harbored in the Great Lakes and surrounding water bodies of the East African Rift System. However, this unique diversity is not reflected in the fossil record because fossil cichlids were predominantly reported based on isolated teeth and bones. Moreover, the few articulated specimens that are known have not been analyzed sufficiently with regard to their systematic position due to lack of comparative material. Here we present a new extraordinarily well-preserved cichlid fish fossil from the Middle Miocene (c. 12.5 Ma Lagerstaette Kabchore, which was recovered during recent fieldwork in the Tugen Hills (Baringo County, Central Kenya Rift. Based on the evidence of tricuspid teeth, the Kabchore fossil can be assigned to the subclade of the Haplotilapiines within the Pseudocrenilabrinae. The multivariate analysis of a large meristic data set, derived from 1014 extant specimens (encompassing all main lineages of Haplotilapiines and usage of available osteological data suggest that this fossil is most likely related to one of the three haplotilapiine tribes Tilapiini, Haplochromini or Oreochromini. Moreover, the fossil specimen closely resembles the extinct cichlid Oreochromis martyni (Van Couvering, 1982, previously described as species of Sarotherodon from the Middle Miocene alkaline Kapkiamu Lake in the Tugen Hills. The analysis of the greatly preserved fossil fish specimen from Kabchore definitely supplements the fragmentary fossil record of Africa’s Cichlidae and will afford new insights into its evolutionary history. We also expect that this fossil will be useful as calibration point for new divergence-time estimates.

Evolution of cichlid vision via trans-regulatory divergence

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O’Quin Kelly E

2012-12-01

Full Text Available Abstract Background Phenotypic evolution may occur through mutations that affect either the structure or expression of protein-coding genes. Although the evolution of color vision has historically been attributed to structural mutations within the opsin genes, recent research has shown that opsin regulatory mutations can also tune photoreceptor sensitivity and color vision. Visual sensitivity in African cichlid fishes varies as a result of the differential expression of seven opsin genes. We crossed cichlid species that express different opsin gene sets and scanned their genome for expression Quantitative Trait Loci (eQTL responsible for these differences. Our results shed light on the role that different structural, cis-, and trans-regulatory mutations play in the evolution of color vision. Results We identified 11 eQTL that contribute to the divergent expression of five opsin genes. On three linkage groups, several eQTL formed regulatory “hotspots” associated with the expression of multiple opsins. Importantly, however, the majority of the eQTL we identified (8/11 or 73% occur on linkage groups located trans to the opsin genes, suggesting that cichlid color vision has evolved primarily via trans-regulatory divergence. By modeling the impact of just two of these trans-regulatory eQTL, we show that opsin regulatory mutations can alter cichlid photoreceptor sensitivity and color vision at least as much as opsin structural mutations can. Conclusions Combined with previous work, we demonstrate that the evolution of cichlid color vision results from the interplay of structural, cis-, and especially trans-regulatory loci. Although there are numerous examples of structural and cis-regulatory mutations that contribute to phenotypic evolution, our results suggest that trans-regulatory mutations could contribute to phenotypic divergence more commonly than previously expected, especially in systems like color vision, where compensatory changes in the

Rapid and Parallel Adaptive Evolution of the Visual System of Neotropical Midas Cichlid Fishes.

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Torres-Dowdall, Julián; Pierotti, Michele E R; Härer, Andreas; Karagic, Nidal; Woltering, Joost M; Henning, Frederico; Elmer, Kathryn R; Meyer, Axel

2017-10-01

Midas cichlid fish are a Central American species flock containing 13 described species that has been dated to only a few thousand years old, a historical timescale infrequently associated with speciation. Their radiation involved the colonization of several clear water crater lakes from two turbid great lakes. Therefore, Midas cichlids have been subjected to widely varying photic conditions during their radiation. Being a primary signal relay for information from the environment to the organism, the visual system is under continuing selective pressure and a prime organ system for accumulating adaptive changes during speciation, particularly in the case of dramatic shifts in photic conditions. Here, we characterize the full visual system of Midas cichlids at organismal and genetic levels, to determine what types of adaptive changes evolved within the short time span of their radiation. We show that Midas cichlids have a diverse visual system with unexpectedly high intra- and interspecific variation in color vision sensitivity and lens transmittance. Midas cichlid populations in the clear crater lakes have convergently evolved visual sensitivities shifted toward shorter wavelengths compared with the ancestral populations from the turbid great lakes. This divergence in sensitivity is driven by changes in chromophore usage, differential opsin expression, opsin coexpression, and to a lesser degree by opsin coding sequence variation. The visual system of Midas cichlids has the evolutionary capacity to rapidly integrate multiple adaptations to changing light environments. Our data may indicate that, in early stages of divergence, changes in opsin regulation could precede changes in opsin coding sequence evolution. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Accelerated Evolution and Functional Divergence of the Dim Light Visual Pigment Accompanies Cichlid Colonization of Central America.

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Hauser, Frances E; Ilves, Katriina L; Schott, Ryan K; Castiglione, Gianni M; López-Fernández, Hernán; Chang, Belinda S W

2017-10-01

Cichlids encompass one of the most diverse groups of fishes in South and Central America, and show extensive variation in life history, morphology, and colouration. While studies of visual system evolution in cichlids have focussed largely on the African rift lake species flocks, Neotropical cichlids offer a unique opportunity to investigate visual system evolution at broader temporal and geographic scales. South American cichlid colonization of Central America has likely promoted accelerated rates of morphological evolution in Central American lineages as they encountered reduced competition, renewed ecological opportunity, and novel aquatic habitats. To investigate whether such transitions have influenced molecular evolution of vision in Central American cichlids, we sequenced the dim-light rhodopsin gene in 101 Neotropical cichlid species, spanning the diversity of the clade. We find strong evidence for increased rates of evolution in Central American cichlid rhodopsin relative to South American lineages, and identify several sites under positive selection in rhodopsin that likely contribute to adaptation to different photic environments. We expressed a Neotropical cichlid rhodopsin protein invitro for the first time, and found that while its spectral tuning properties were characteristic of typical vertebrate rhodopsin pigments, the rate of decay of its active signalling form was much slower, consistent with dim light adaptation in other vertebrate rhodopsins. Using site-directed mutagenesis combined with spectroscopic assays, we found that a key amino acid substitution present in some Central American cichlids accelerates the rate of decay of active rhodopsin, which may mediate adaptation to clear water habitats. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Contrasting parasite communities among allopatric colour morphs of the Lake Tanganyika cichlid Tropheus.

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Raeymaekers, Joost A M; Hablützel, Pascal I; Grégoir, Arnout F; Bamps, Jolien; Roose, Anna K; Vanhove, Maarten P M; Van Steenberge, Maarten; Pariselle, Antoine; Huyse, Tine; Snoeks, Jos; Volckaert, Filip A M

2013-02-14

Adaptation to different ecological environments is thought to drive ecological speciation. This phenomenon culminates in the radiations of cichlid fishes in the African Great Lakes. Multiple characteristic traits of cichlids, targeted by natural or sexual selection, are considered among the driving factors of these radiations. Parasites and pathogens have been suggested to initiate or accelerate speciation by triggering both natural and sexual selection. Three prerequisites for parasite-driven speciation can be inferred from ecological speciation theory. The first prerequisite is that different populations experience divergent infection levels. The second prerequisite is that these infection levels cause divergent selection and facilitate adaptive divergence. The third prerequisite is that parasite-driven adaptive divergence facilitates the evolution of reproductive isolation. Here we investigate the first and the second prerequisite in allopatric chromatically differentiated lineages of the rock-dwelling cichlid Tropheus spp. from southern Lake Tanganyika (Central Africa). Macroparasite communities were screened in eight populations belonging to five different colour morphs. Parasite communities were mainly composed of acanthocephalans, nematodes, monogeneans, copepods, branchiurans, and digeneans. In two consecutive years (2011 and 2012), we observed significant variation across populations for infection with acanthocephalans, nematodes, monogeneans of the genera Gyrodactylus and Cichlidogyrus, and the copepod Ergasilus spp. Overall, parasite community composition differed significantly between populations of different colour morphs. Differences in parasite community composition were stable in time. The genetic structure of Tropheus populations was strong and showed a significant isolation-by-distance pattern, confirming that spatial isolation is limiting host dispersal. Correlations between parasite community composition and Tropheus genetic differentiation were

The genetic and developmental basis of an exaggerated craniofacial trait in East African cichlids.

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Concannon, Moira R; Albertson, R Craig

2015-12-01

The evolution of an exaggerated trait can lead to a novel morphology that allows organisms to exploit new niches. The molecular bases of such phenotypes can reveal insights into the evolution of unique traits. Here, we investigate a rare morphological innovation in modern haplochromine cichlids, a flap of fibrous tissue that causes a pronounced projection of the snout, which is limited to a single genus (Labeotropheus) of Lake Malawi cichlids. We compare flap size in our focal species L. fuelleborni (LF) to homologous landmarks in other closely related cichlid species that show a range of ecological overlap with LF, and demonstrate that variation in flap size is discontinuous among Malawi cichlid species. We demonstrate further that flap development in LF begins at early juvenile stages, and scales allometrically with body size. We then used an F2 hybrid mapping population, derived via crossing LF to a close ecological competitor that lacks this trait, Tropheops "red cheek" (TRC), to identify quantitative trait loci (QTL) that underlie flap development. In all, we identified four loci associated with variation in flap size, and for each the LF allele contributed to a larger flap. We next cross-referenced our QTL map with population genomic data, comparing natural populations of LF and TRC, to identify divergent polymorphisms within each QTL interval. Candidate genes for flap development are discussed. Together, these data indicate a relatively simple and tractable genetic basis for this morphological innovation, which is consistent with its apparently sudden and saltatory evolutionary history. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 662-670, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Adaptive responses to environmental changes in Lake Victoria cichlids

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Rijssel, Jacobus Cornelis van (Jacco)

2014-01-01

Lake Victoria cichlids show the fastest vertebrate adaptive radiation known which is why they function as a model organism to study evolution. In the past 40 years, Lake Victoria experienced severe environmental changes including the boom of the introduced, predatory Nile perch and eutrophication.

Niche divergence facilitated by fine-scale ecological partitioning in a recent cichlid fish adaptive radiation.

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Ford, Antonia G P; Rüber, Lukas; Newton, Jason; Dasmahapatra, Kanchon K; Balarin, John D; Bruun, Kristoffer; Day, Julia J

2016-12-01

Ecomorphological differentiation is a key feature of adaptive radiations, with a general trend for specialization and niche expansion following divergence. Ecological opportunity afforded by invasion of a new habitat is thought to act as an ecological release, facilitating divergence, and speciation. Here, we investigate trophic adaptive morphology and ecology of an endemic clade of oreochromine cichlid fishes (Alcolapia) that radiated along a herbivorous trophic axis following colonization of an isolated lacustrine environment, and demonstrate phenotype-environment correlation. Ecological and morphological divergence of the Alcolapia species flock are examined in a phylogenomic context, to infer ecological niche occupation within the radiation. Species divergence is observed in both ecology and morphology, supporting the importance of ecological speciation within the radiation. Comparison with an outgroup taxon reveals large-scale ecomorphological divergence but shallow genomic differentiation within the Alcolapia adaptive radiation. Ancestral morphological reconstruction suggests lake colonization by a generalist oreochromine phenotype that diverged in Lake Natron to varied herbivorous morphologies akin to specialist herbivores in Lakes Tanganyika and Malawi. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Antipredator responses by native mosquitofish to non-native cichlids: An examination of the role of prey naiveté

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Rehage, Jennifer S.; Dunlop, Katherine L.; Loftus, William F.

2009-01-01

The strong impact of non-native predators in aquatic systems is thought to relate to the evolutionary naiveté of prey. Due to isolation and limited dispersal, this naiveté may be relatively high in freshwater systems. In this study, we tested this notion by examining the antipredator response of native mosquitofish, Gambusia holbrooki, to two non-native predators found in the Everglades, the African jewelfish,Hemichromis letourneuxi, and the Mayan cichlid, Cichlasoma urophthalmus. We manipulated prey naiveté by using two mosquitofish populations that varied in their experience with the recent invader, the African jewelfish, but had similar levels of experience with the longer-established Mayan cichlid. Specifically, we tested these predictions: (1) predator hunting modes differed between the two predators, (2) predation rates would be higher by the novel jewelfish predator, (3) particularly on the naive population living where jewelfish have not invaded yet, (4) antipredator responses would be stronger to Mayan cichlids due to greater experience and weaker and/or ineffective to jewelfish, and (5) especially weakest by the naive population. We assayed prey and predator behavior, and prey mortality in lab aquaria where both predators and prey were free-ranging. Predator hunting modes and habitat domains differed, with jewelfish being more active search predators that used slightly higher parts of the water column and less of the habitat structure relative to Mayan cichlids. In disagreement with our predictions, predation rates were similar between the two predators, antipredator responses were stronger to African jewelfish (except for predator inspections), and there was no difference in response between jewelfish-savvy and jewelfish-naive populations. These results suggest that despite the novelty of introduced predators, prey may be able to respond appropriately if non-native predator archetypes are similar enough to those of native predators, if prey rely

Social regulation of male reproductive plasticity in an African cichlid fish.

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Maruska, Karen P; Fernald, Russell D

2013-12-01

Social interactions with the outcome of a position in a dominance hierarchy can have profound effects on reproductive behavior and physiology, requiring animals to integrate environmental information with their internal physiological state; but how is salient information from the animal's dynamic social environment transformed into adaptive behavioral, physiological, and molecular-level changes? The African cichlid fish, Astatotilapia burtoni, is ideally suited to understand socially controlled reproductive plasticity because activity of the male reproductive (brain-pituitary-gonad) axis is tightly linked to social status. Males form hierarchies in which a small percentage of brightly colored dominant individuals have an active reproductive axis, defend territories, and spawn with females, while the remaining males are subordinate, drably colored, do not hold a territory, and have a suppressed reproductive system with minimal opportunities for spawning. These social phenotypes are plastic and quickly reversible, meaning that individual males may switch between dominant and subordinate status multiple times within a lifetime. Here, we review the rapid and remarkable plasticity that occurs along the entire reproductive axis when males rise in social rank, a transition that has important implications for the operational sex ratio of the population. When males rise in rank, transformations occur in the brain, pituitary, circulation, and testes over short time-scales (minutes to days). Changes are evident in overt behavior, as well as modifications at the physiological, cellular, and molecular levels that regulate reproductive capacity. Widespread changes triggered by a switch in rank highlight the significance of external social information in shaping internal physiology and reproductive competence.

Retroposition of the AFC family of SINEs (short interspersed repetitive elements) before and during the adaptive radiation of cichlid fishes in Lake Malawi and related inferences about phylogeny.

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Takahashi, K; Nishida, M; Yuma, M; Okada, N

2001-01-01

Lake Malawi is home to more than 450 species of endemic cichlids, which provide a spectacular example of adaptive radiation. To clarify the phylogenetic relationships among these fish, we examined the presence and absence of SINEs (short interspersed repetitive elements) at orthologous loci. We identified six loci at which a SINE sequence had apparently been specifically inserted by retroposition in the common ancestor of all the investigated species of endemic cichlids in Lake Malawi. At another locus, unique sharing of a SINE sequence was evident among all the investigated species of endemic non-Mbuna cichlids with the exception of Rhamphochromis sp. The relationships were in good agreement with those deduced in previous studies with various different markers, demonstrating that the SINE method is useful for the elucidation of phylogenetic relationships among cichlids in Lake Malawi. We also characterized a locus that exhibited transspecies polymorphism with respect to the presence or absence of the SINE sequence among non-Mbuna species. This result suggests that incomplete lineage sorting and/or interspecific hybridization might have occurred or be occurring among the species in this group, which might potentially cause misinterpretation of phylogenetic data, in particular when a single-locus marker, such as a sequence in the mitochondrial DNA, is used for analysis.

Success of cuckoo catfish brood parasitism reflects coevolutionary history and individual experience of their cichlid hosts

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Polačik, Matej; Smith, Carl; Honza, Marcel; Reichard, Martin

2018-01-01

Obligate brood parasites manipulate other species into raising their offspring. Avian and insect brood parasitic systems demonstrate how interacting species engage in reciprocal coevolutionary arms races through behavioral and morphological adaptations and counteradaptations. Mouthbrooding cichlid fishes are renowned for their remarkable evolutionary radiations and complex behaviors. In Lake Tanganyika, mouthbrooding cichlids are exploited by the only obligate nonavian vertebrate brood parasite, the cuckoo catfish Synodontis multipunctatus. We show that coevolutionary history and individual learning both have a major impact on the success of cuckoo catfish parasitism between coevolved sympatric and evolutionarily naïve allopatric cichlid species. The rate of cuckoo catfish parasitism in coevolved Tanganyikan hosts was 3 to 11 times lower than in evolutionarily naïve cichlids. Moreover, using experimental infections, we demonstrate that parasite egg rejection in sympatric hosts was much higher, leading to seven times greater parasite survival in evolutionarily naïve than sympatric hosts. However, a high rejection frequency of parasitic catfish eggs by coevolved sympatric hosts came at a cost of increased rejection of their own eggs. A significant cost of catfish parasitism was universal, except for coevolved sympatric cichlid species with previous experience of catfish parasitism, demonstrating that learning and individual experience both contribute to a successful host response.

Hidden biodiversity in an ancient lake: phylogenetic congruence between Lake Tanganyika tropheine cichlids and their monogenean flatworm parasites.

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Vanhove, Maarten P M; Pariselle, Antoine; Van Steenberge, Maarten; Raeymaekers, Joost A M; Hablützel, Pascal I; Gillardin, Céline; Hellemans, Bart; Breman, Floris C; Koblmüller, Stephan; Sturmbauer, Christian; Snoeks, Jos; Volckaert, Filip A M; Huyse, Tine

2015-09-03

The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the body surface and gills of fishes. In contrast to many other parasites, they depend only on a single host species to complete their lifecycle. Our spatially comprehensive combined nuclear-mitochondrial DNA dataset of the parasites covering almost all tropheine host species (N = 18), reveals species-rich parasite assemblages and shows consistent host-specificity. Statistical comparisons of host and parasite phylogenies based on distance and topology-based tests demonstrate significant congruence and suggest that host-switching is rare. Molecular rate evaluation indicates that species of Cichlidogyrus probably diverged synchronically with the initial radiation of the tropheines. They further diversified through within-host speciation into an overlooked species radiation. The unique life history and specialisation of certain parasite groups has profound evolutionary consequences. Hence, evolutionary parasitology adds a new dimension to the study of biodiversity hotspots like Lake Tanganyika.

Are sympatrically speciating Midas cichlid fish special? Patterns of morphological and genetic variation in the closely related species Archocentrus centrarchus.

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Fruciano, Carmelo; Franchini, Paolo; Raffini, Francesca; Fan, Shaohua; Meyer, Axel

2016-06-01

Established empirical cases of sympatric speciation are scarce, although there is an increasing consensus that sympatric speciation might be more common than previously thought. Midas cichlid fish are one of the few substantiated cases of sympatric speciation, and they formed repeated radiations in crater lakes. In contrast, in the same environment, such radiation patterns have not been observed in other species of cichlids and other families of fish. We analyze morphological and genetic variation in a cichlid species (Archocentrus centrarchus) that co-inhabits several crater lakes with the Midas species complex. In particular, we analyze variation in body and pharyngeal jaw shape (two ecologically important traits in sympatrically divergent Midas cichlids) and relate that to genetic variation in mitochondrial control region and microsatellites. Using these four datasets, we analyze variation between and within two Nicaraguan lakes: a crater lake where multiple Midas cichlids have been described and a lake where the source population lives. We do not observe any within-lake clustering consistent across morphological traits and genetic markers, suggesting the absence of sympatric divergence in A. centrarchus. Genetic differentiation between lakes was low and morphological divergence absent. Such morphological similarity between lakes is found not only in average morphology, but also when analyzing covariation between traits and degree of morphospace occupation. A combined analysis of the mitochondrial control region in A. centrarchus and Midas cichlids suggests that a difference between lineages in the timing of crater lake colonization cannot be invoked as an explanation for the difference in their levels of diversification. In light of our results, A. centrarchus represents the ideal candidate to study the genomic differences between these two lineages that might explain why some lineages are more likely to speciate and diverge in sympatry than others.

B chromosomes have a functional effect on female sex determination in Lake Victoria cichlid fishes.

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Kohta Yoshida

2011-08-01

Full Text Available The endemic cichlid fishes in Lake Victoria are a model system for speciation through adaptive radiation. Although the evolution of the sex-determination system may also play a role in speciation, little is known about the sex-determination system of Lake Victoria cichlids. To understand the evolution of the sex-determination system in these fish, we performed cytogenetic analysis in 11 cichlid species from Lake Victoria. B chromosomes, which are present in addition to standard chromosomes, were found at a high prevalence rate (85% in these cichlids. In one species, B chromosomes were female-specific. Cross-breeding using females with and without the B chromosomes demonstrated that the presence of the B chromosomes leads to a female-biased sex ratio in this species. Although B chromosomes were believed to be selfish genetic elements with little effect on phenotype and to lack protein-coding genes, the present study provides evidence that B chromosomes have a functional effect on female sex determination. FISH analysis using a BAC clone containing B chromosome DNA suggested that the B chromosomes are derived from sex chromosomes. Determination of the nucleotide sequences of this clone (104.5 kb revealed the presence of several protein-coding genes in the B chromosome, suggesting that B chromosomes have the potential to contain functional genes. Because some sex chromosomes in amphibians and arthropods are thought to be derived from B chromosomes, the B chromosomes in Lake Victoria cichlids may represent an evolutionary transition toward the generation of sex chromosomes.

Correlated evolution of short wavelength sensitive photoreceptor sensitivity and color pattern in Lake Malawi cichlids

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Michael J. Pauers

2016-02-01

Full Text Available For evolutionary ecologists, the holy grail of visual ecology is to establish an unambiguous link between photoreceptor sensitivity, the spectral environment, and the perception of specific visual stimuli (e.g., mates, food, predators, etc.. Due to the bright nuptial colors of the males, and the role female mate choice plays in their evolution, the haplochromine cichlid fishes of the African great lakes are favorite research subjects for such investigations. Despite this attention, current evidence is equivocal; while distinct correlations among photoreceptor sensitivity, photic environment, and male coloration exist in Lake Victorian haplochromines, attempts to find such correlations in Lake Malawian cichlids have failed. Lake Malawi haplochromines have a wide variability in their short-wavelength-sensitive photoreceptors, especially compared to their mid- and long-wavelength-sensitive photoreceptors; these cichlids also vary in the degree to which they express one of three basic color patterns (vertical bars, horizontal stripes, and solid patches of colors, each of which is likely used in a different form of communication. Thus, we hypothesize that, in these fishes, spectral sensitivity and color pattern have evolved in a correlated fashion to maximize visual communication; specifically, ultraviolet sensitivity should be found in vertically-barred species to promote ‘private’ communication, while striped species should be less likely to have ultraviolet sensitivity, since their color pattern carries ‘public’ information. Using phylogenetic independent contrasts, we found that barred species had strong sensitivity to ultraviolet wavelengths, but that striped species typically lacked sensitivity to ultraviolet light. Further, the only variable, even when environmental variables were simultaneously considered, that could predict ultraviolet sensitivity was color pattern. We also found that, using models of correlated evolution, color

A gene expression study of dorso-ventrally restricted pigment pattern in adult fins of Neolamprologus meeli, an African cichlid species

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Ehsan Pashay Ahi

2017-01-01

Full Text Available Fish color patterns are among the most diverse phenotypic traits found in the animal kingdom. Understanding the molecular and cellular mechanisms that control in chromatophore distribution and pigmentation underlying this diversity is a major goal in developmental and evolutionary biology, which has predominantly been pursued in the zebrafish model system. Here, we apply results from zebrafish work to study a naturally occurring color pattern phenotype in the fins of an African cichlid species from Lake Tanganyika. The cichlid fish Neolamprologus meeli displays a distinct dorsal color pattern, with black and white stripes along the edges of the dorsal fin and of the dorsal half of the caudal fin, corresponding with differences in melanophore density. To elucidate the molecular mechanisms controlling the differences in dorsal and ventral color patterning in the fins, we quantitatively assessed the expression of 15 candidate target genes involved in adult zebrafish pigmentation and stripe formation. For reference gene validation, we screened the expression stability of seven widely expressed genes across the investigated tissue samples and identified tbp as appropriate reference. Relative expression levels of the candidate target genes were compared between the dorsal, striped fin regions and the corresponding uniform, grey-colored regions in the anal and ventral caudal fin. Dorso-ventral expression differences, with elevated levels in both white and black stripes, were observed in two genes, the melanosome protein coding gene pmel and in igsf11, which affects melanophore adhesion, migration and survival. Next, we predicted potential shared upstream regulators of pmel and igsf11. Testing the expression patterns of six predicted transcriptions factors revealed dorso-ventral expression difference of irf1 and significant, negative expression correlation of irf1 with both pmel and igsf11. Based on these results, we propose pmel, igsf11 and irf1 as

Characterization of V1R receptor (ora) genes in Lake Victoria cichlids.

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Ota, Tomoki; Nikaido, Masato; Suzuki, Hikoyu; Hagino-Yamagishi, Kimiko; Okada, Norihiro

2012-05-15

Although olfaction could play a crucial role in underwater habitats by allowing fish to sense a variety of nonvolatile chemical signals, the importance of olfaction in species-rich cichlids is still controversial. In particular, examining whether cichlids rely on olfaction for reproduction is of primary interest to understand the mechanisms of speciation. In the present study, we explored the V1R (also known as ora) genes, which are believed to encode reproductive pheromone receptors in fish, in the genomes of Lake Victoria cichlids. By screening a bacterial artificial chromosome library, we identified all six intact V1R genes (V1R1 to V1R6) that have been reported in other teleost fish. Furthermore, RT-PCR and in situ hybridization analyses showed that all of the V1R genes were expressed in the olfactory epithelium, indicating that these receptors are functional in cichlids. These observations indicate that cichlids use V1R-mediated olfaction in some ways for their social behaviors. Copyright © 2012 Elsevier B.V. All rights reserved.

Tol2 transposon-mediated transgenesis in the Midas cichlid (Amphilophus citrinellus) - towards understanding gene function and regulatory evolution in an ecological model system for rapid phenotypic diversification.

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Kratochwil, Claudius F; Sefton, Maggie M; Liang, Yipeng; Meyer, Axel

2017-11-23

The Midas cichlid species complex (Amphilophus spp.) is widely known among evolutionary biologists as a model system for sympatric speciation and adaptive phenotypic divergence within extremely short periods of time (a few hundred generations). The repeated parallel evolution of adaptive phenotypes in this radiation, combined with their near genetic identity, makes them an excellent model for studying phenotypic diversification. While many ecological and evolutionary studies have been performed on Midas cichlids, the molecular basis of specific phenotypes, particularly adaptations, and their underlying coding and cis-regulatory changes have not yet been studied thoroughly. For the first time in any New World cichlid, we use Tol2 transposon-mediated transgenesis in the Midas cichlid (Amphilophus citrinellus). By adapting existing microinjection protocols, we established an effective protocol for transgenesis in Midas cichlids. Embryos were injected with a Tol2 plasmid construct that drives enhanced green fluorescent protein (eGFP) expression under the control of the ubiquitin promoter. The transgene was successfully integrated into the germline, driving strong ubiquitous expression of eGFP in the first transgenic Midas cichlid line. Additionally, we show transient expression of two further transgenic constructs, ubiquitin::tdTomato and mitfa::eGFP. Transgenesis in Midas cichlids will facilitate further investigation of the genetic basis of species-specific traits, many of which are adaptations. Transgenesis is a versatile tool not only for studying regulatory elements such as promoters and enhancers, but also for testing gene function through overexpression of allelic gene variants. As such, it is an important first step in establishing the Midas cichlid as a powerful model for studying adaptive coding and non-coding changes in an ecological and evolutionary context.

Cichlid Fishes in the Angolan Headwaters Region: Molecular Evidence of the Ichthyofaunal Contact between the Cuanza and Okavango-Zambezi Systems

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Musilová, Zuzana; Kalous, Lukáš; Petrtýl, Miloslav; Chaloupková, Petra

2013-01-01

The headwaters of five large African river basins flow through the Bié Plateau in Angola and still remain faunistically largely unexplored. We investigated fish fauna from the Cuanza and Okavango-Zambezi river systems from central Angola. We reconstructed molecular phylogenies of the most common cichlid species from the region, Tilapia sparrmanii and Serranochromis macrocephalus, using both mitochondrial and nuclear markers. We found evidence for ichthyofaunal contact and gene flow between the Cuanza and Okavango-Zambezi watersheds in the Bié Plateau in central Angola. Waterfalls and rapids also appeared to restrict genetic exchange among populations within the Cuanza basin. Further, we found that the Angolan Serranochromis cichlid fishes represent a monophyletic lineage with respect to other haplochromines, including the serranochromines from the Congo and Zambezi rivers. This study represents an important initial step in a biodiversity survey of this extremely poorly explored region, as well as giving further understanding to species distributions and gene flow both between and within river basins. PMID:23724120

Transcriptomics of morphological color change in polychromatic Midas cichlids.

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Henning, Frederico; Jones, Julia C; Franchini, Paolo; Meyer, Axel

2013-03-13

Animal pigmentation has received much attention in evolutionary biology research due to its strong implications for adaptation and speciation. However, apart from a few cases the genetic changes associated with these evolutionary processes remain largely unknown. The Midas cichlid fish from Central America are an ideal model system for investigating pigmentation traits that may also play a role in speciation. Most Midas cichlids maintain their melanophores and exhibit a grayish (normal) color pattern throughout their lives. A minority of individuals, however, undergo color change and exhibit a distinctive gold or even white coloration in adulthood. The ontogenetic color change in the Midas cichlids may also shed light on the molecular mechanisms underlying pigmentation disorders in humans. Here we use next-generation sequencing (Illumina) RNAseq analyses to compare skin transcriptome-wide expression levels in three distinct stages of color transformation in Midas cichlids. cDNA libraries of scale tissue, for six biological replicates of each group, were generated and sequenced using Illumina technology. Using a combination of three differential expression (DE) analyses we identified 46 candidate genes that showed DE between the color morphs. We find evidence for two key DE patterns: a) genes involved in melanosomal pathways are up-regulated in normally pigmented fish; and b) immediate early and inflammatory response genes were up-regulated in transitional fish, a response that parallels some human skin disorders such as melanoma formation and psoriasis. One of the DE genes segregates with the gold phenotype in a genetic cross and might be associated with incipient speciation in this highly "species-rich" lineage of cichlids. Using transcriptomic analyses we successfully identified key expression differences between different color morphs of Midas cichlid fish. These differentially expressed genes have important implications for our understanding of the molecular

Phylogeography, colonization and population history of the Midas cichlid species complex (Amphilophus spp. in the Nicaraguan crater lakes

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Meyer Axel

2010-10-01

Full Text Available Abstract Background Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex Amphilophus spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phylogeographic analysis of the complete Midas Cichlid species complex in Nicaragua (> 2000 individuals covering the entire distributional range, using two types of molecular markers (the mitochondrial DNA control region and 15 microsatellites. We investigated the majority of known lake populations of this species complex and reconstructed their colonization history in order to distinguish between alternative speciation scenarios. Results We found that the large lakes contain older and more diverse Midas Cichlid populations, while all crater lakes hold younger and genetically less variable species assemblages. The large lakes appear to have repeatedly acted as source populations for all crater lakes, and our data indicate that faunal exchange among crater lakes is extremely unlikely. Despite their very recent (often only a few thousand years old and common origin from the two large Nicaraguan lakes, all crater lake Midas Cichlid radiations underwent independent, but parallel, evolution, and comprise distinct genetic units. Indeed several of these crater lakes contain multiple genetically distinct incipient species that most likely arose through sympatric speciation. Several crater lake radiations can be traced back to a single ancestral line, but some appear to have more than one founding lineage. The timing of the colonization(s of each crater lake differs, although most of them occurred more (probably much more recently than 20,000 years ago. Conclusion The

Phylogeography, colonization and population history of the Midas cichlid species complex (Amphilophus spp.) in the Nicaraguan crater lakes.

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Barluenga, Marta; Meyer, Axel

2010-10-26

Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex Amphilophus spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phylogeographic analysis of the complete Midas Cichlid species complex in Nicaragua (> 2000 individuals) covering the entire distributional range, using two types of molecular markers (the mitochondrial DNA control region and 15 microsatellites). We investigated the majority of known lake populations of this species complex and reconstructed their colonization history in order to distinguish between alternative speciation scenarios. We found that the large lakes contain older and more diverse Midas Cichlid populations, while all crater lakes hold younger and genetically less variable species assemblages. The large lakes appear to have repeatedly acted as source populations for all crater lakes, and our data indicate that faunal exchange among crater lakes is extremely unlikely. Despite their very recent (often only a few thousand years old) and common origin from the two large Nicaraguan lakes, all crater lake Midas Cichlid radiations underwent independent, but parallel, evolution, and comprise distinct genetic units. Indeed several of these crater lakes contain multiple genetically distinct incipient species that most likely arose through sympatric speciation. Several crater lake radiations can be traced back to a single ancestral line, but some appear to have more than one founding lineage. The timing of the colonization(s) of each crater lake differs, although most of them occurred more (probably much more) recently than 20,000 years ago. The genetic differentiation of the crater lake populations

The evolution of cooperative breeding in the African cichlid fish, Neolamprologus pulcher.

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Wong, Marian; Balshine, Sigal

2011-05-01

The conundrum of why subordinate individuals assist dominants at the expense of their own direct reproduction has received much theoretical and empirical attention over the last 50 years. During this time, birds and mammals have taken centre stage as model vertebrate systems for exploring why helpers help. However, fish have great potential for enhancing our understanding of the generality and adaptiveness of helping behaviour because of the ease with which they can be experimentally manipulated under controlled laboratory and field conditions. In particular, the freshwater African cichlid, Neolamprologus pulcher, has emerged as a promising model species for investigating the evolution of cooperative breeding, with 64 papers published on this species over the past 27 years. Here we clarify current knowledge pertaining to the costs and benefits of helping in N. pulcher by critically assessing the existing empirical evidence. We then provide a comprehensive examination of the evidence pertaining to four key hypotheses for why helpers might help: (1) kin selection; (2) pay-to-stay; (3) signals of prestige; and (4) group augmentation. For each hypothesis, we outline the underlying theory, address the appropriateness of N. pulcher as a model species and describe the key predictions and associated empirical tests. For N. pulcher, we demonstrate that the kin selection and group augmentation hypotheses have received partial support. One of the key predictions of the pay-to-stay hypothesis has failed to receive any support despite numerous laboratory and field studies; thus as it stands, the evidence for this hypothesis is weak. There have been no empirical investigations addressing the key predictions of the signals of prestige hypothesis. By outlining the key predictions of the various hypotheses, and highlighting how many of these remain to be tested explicitly, our review can be regarded as a roadmap in which potential paths for future empirical research into the

A sensory bias has triggered the evolution of egg-spots in cichlid fishes.

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Bernd Egger

Full Text Available Although, generally, the origin of sex-limited traits remains elusive, the sensory exploitation hypothesis provides an explanation for the evolution of male sexual signals. Anal fin egg-spots are such a male sexual signal and a key characteristic of the most species-rich group of cichlid fishes, the haplochromines. Males of about 1500 mouth-brooding species utilize these conspicuous egg-dummies during courtship--apparently to attract females and to maximize fertilization success. Here we test the hypothesis that the evolution of haplochromine egg-spots was triggered by a pre-existing bias for eggs or egg-like coloration. To this end, we performed mate-choice experiments in the basal haplochromine Pseudocrenilabrus multicolor, which manifests the plesiomorphic character-state of an egg-spot-less anal fin. Experiments using computer-animated photographs of males indeed revealed that females prefer images of males with virtual ('in-silico' egg-spots over images showing unaltered males. In addition, we tested for color preferences (outside a mating context in a phylogenetically representative set of East African cichlids. We uncovered a strong preference for yellow, orange or reddish spots in all haplochromines tested and, importantly, also in most other species representing more basal lines. This pre-existing female sensory bias points towards high-quality (carotenoids-enriched food suggesting that it is adaptive.

Fish embryo and juvenile size under hypoxia in the mouth-brooding African cichlid Pseudocrenilabrus multicolor

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E.E.REARDON; L.J.CHAPMAN

2012-01-01

We used a field survey and a laboratory rearing experiment to (a) examine response (size and survival) to life-long hypoxia in offspring of the African maternal mouth-brooding cichlid Pseudocrenilabrus multicolor victoriae (Seegers) and (b) explore the degree to which developmental response can be environmentally-induced.Embryo size metrics were quantified in 9 field populations across a range of dissolved oxygen (DO) concentrations.In the laboratory,first generation (F1) broods of low-DO origin were reared under high or low DO.Brooding period was quantified for the mothers; and egg size,egg metabolic rate and juvenile size-at-release were quantified in their (F2) offspring.The F2 offspring were split and grown for 3 months post-release under high or low DO,and juvenile size and survival were quantified.In the field survey,across stages,embryos from low-DO field populations were shorter and weighed less than embryos from high-DO populations.In the laboratory experiment,F2 eggs and juveniles-at-release from mother's mouth did not differ in mass,length,survival regardless of development DO environment.However,juveniles diverged in size after leaving mother's mouth,exhibiting smaller size when grown under low DO.Size differences in embryo size across field populations and divergence in embryo size after release from the mother's mouthsupport predictions for smaller body size under hypoxia.There was no evidence for negative effects on survival of juveniles after 3 months.Brooding period was 16％ shorter in females reared under low DO suggesting that hypoxia may accelerate embryo development.This work provides insights into how bearer fishes respond to hypoxic stress relative to fishes with no post-spawning parental care; a shorter brooding interval and smaller body size may provide an optimal solution to parent and embryo survival under hypoxia in brooding fishes.

Range expansion of the Mayan cichlid, cichlasoma urophthalmus (pisces, cichlidae), above 28°N in Florida

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Paperno, R.; Ruiz-Carus, R.; Krebs, J.M.; McIvor, C.C.

2008-01-01

Introduced exotic species are a well-recognized problem in Florida's subtropical ecosystems. The presence of the exotic Mayan cichlid (Cichlasoma urophthalmus) was first confirmed in Florida in 1983, when numerous individuals were found in the northeastern Florida Bay. Since then, this species has continued to expand its range northward. The capture, beginning in October 2004 to present, of large numbers of Mayan cichlids from central Florida's east- and west-coast mangrove systems north of 28°N latitude is documented here. Mayan cichlids in a wide range of sizes (estimated ages 0-7 years) at both east- and west-coast sites were collected. In addition, macroscopic examination of gonads showed the presence of developing eggs. The occurrence of multiple age-classes, maturing individuals, cichlid nests, and juveniles, plus repeated collections over a four-year period, indicates that the Mayan cichlid is successfully reproducing and surviving the average winter temperatures in some estuarine waters in central Florida.

Biological Diversity and Resilience: Lessons from the Recovery of Cichlid Species in Lake Victoria

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Alex O. Awiti

2011-03-01

Full Text Available A fundamental feature of the Anthropocene is the inexorable erosion of the self-repairing capacity or adaptive renewal of natural systems because of natural perturbation, exploitation, or management failure. The concept of resilience offers a systematic framework for understanding the dynamics and variables that govern response dynamics of ecosystems. Resilience of haplochromine cichlids is assessed using limnological and biodiversity changes in Lake Victoria, the world's second largest freshwater lake, over the last five decades. The review explores the resurgence of the haplochromine cichlids using Holling's adaptive renewal cycle and attempts to illustrate how resilience-based management approaches might learn from an inadvertent management experiment. The introduction in the 1980s of the Nile perch (Lates niloticus, a fecund and voracious predator of the endemic phytoplankton feeding haplochromine cichlids, anthropogenic eutrophication, and deep water hypoxia have combined in a synergistic way to increase the vulnerability of the lake ecosystem to perturbations that were hitherto absorbed. However, the upsurge in commercial Nile perch fishing appears to be enabling the resurgence of the haplochromine cichlids. The resurgence of haplochromine cichlids is characterized by phenotypic plasticity, ecological and life history traits and demonstrates the critical role of response diversity in the maintenance of systems resilience. Resilience of the haplochromine cichlids resides in the requisite functional response diversity and habitat diversity that provide the resources for renewal and regeneration. This paper concludes that management of Nile perch fisheries and control of nutrient loading into Lake Victoria could halt or reverse eutrophication, hence offer the best promise for a diverse, productive, and resilient social-ecological system.

Fish embryo and juvenile size under hypoxia in the mouth- brooding African cichlid Pseudocrenilabrus multicolor

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E.E. REARDON, L.J. CHAPMAN

2012-06-01

Full Text Available We used a field survey and a laboratory rearing experiment to (a examine response (size and survival to life-long hypoxia in offspring of the African maternal mouth-brooding cichlid Pseudocrenilabrus multicolor victoriae (Seegers and (b explore the degree to which developmental response can be environmentally-induced. Embryo size metrics were quantified in 9 field populations across a range of dissolved oxygen (DO concentrations. In the laboratory, first generation (F1 broods of low-DO origin were reared under high or low DO. Brooding period was quantified for the mothers; and egg size, egg metabolic rate and juvenile size-at-release were quantified in their (F2 offspring. The F2 offspring were split and grown for 3 months post-release under high or low DO, and juvenile size and survival were quantified. In the field survey, across stages, embryos from low-DO field populations were shorter and weighed less than embryos from high-DO populations. In the laboratory experiment, F2 eggs and juveniles-at-release from mother’s mouth did not differ in mass, length, survival regardless of development DO environment. However, juveniles diverged in size after leaving mother’s mouth, exhibiting smaller size when grown under low DO. Size differences in embryo size across field populations and divergence in embryo size after release from the mother’s mouth support predictions for smaller body size under hypoxia. There was no evidence for negative effects on survival of juveniles after 3 months. Brooding period was 16% shorter in females reared under low DO suggesting that hypoxia may accelerate embryo development. This work provides insights into how bearer fishes respond to hypoxic stress relative to fishes with no post-spawning parental care; a shorter brooding interval and smaller body size may provide an optimal solution to parent and embryo survival under hypoxia in brooding fishes [Current Zoology 58 (3: 401-412, 2012].

Incipient speciation driven by hypertrophied lips in Midas cichlid fishes?

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Machado-Schiaffino, Gonzalo; Kautt, Andreas F; Torres-Dowdall, Julian; Baumgarten, Lukas; Henning, Frederico; Meyer, Axel

2017-04-01

Sympatric speciation has been debated in evolutionary biology for decades. Although it has gained in acceptance recently, still only a handful of empirical examples are seen as valid (e.g. crater lake cichlids). In this study, we disentangle the role of hypertrophied lips in the repeated adaptive radiations of Nicaraguan crater lake cichlid fish. We assessed the role of disruptive selection and assortative mating during the early stages of divergence and found a functional trade-off in feeding behaviour between thick- and thin-lipped ecotypes, suggesting that this trait is a target of disruptive selection. Thick-lipped fish perform better on nonevasive prey at the cost of a poorer performance on evasive prey. Using enclosures in the wild, we found that thick-lipped fish perform significantly better in rocky than in sandy habitats. We found almost no mixed pairs during two breeding seasons and hence significant assortative mating. Genetic differentiation between ecotypes seems to be related to the time since colonization, being subtle in L. Masaya (1600 generations ago) and absent in the younger L. Apoyeque (<600 generations ago). Genome-wide differentiation between ecotypes was higher in the old source lakes than in the young crater lakes. Our results suggest that hypertrophied lips might be promoting incipient sympatric speciation through divergent selection (ecological divergence in feeding performance) and nonrandom mating (assortative mating) in the young Nicaraguan crater lakes. Nonetheless, further manipulative experiments are needed in order to confirm the role of hypertrophied lips as the main cue for assortative mating. © 2017 John Wiley & Sons Ltd.

Selection towards different adaptive optima drove the early diversification of locomotor phenotypes in the radiation of Neotropical geophagine cichlids.

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Astudillo-Clavijo, Viviana; Arbour, Jessica H; López-Fernández, Hernán

2015-05-01

Simpson envisaged a conceptual model of adaptive radiation in which lineages diversify into "adaptive zones" within a macroevolutionary adaptive landscape. However, only a handful of studies have empirically investigated this adaptive landscape and its consequences for our interpretation of the underlying mechanisms of phenotypic evolution. In fish radiations the evolution of locomotor phenotypes may represent an important dimension of ecomorphological diversification given the implications of locomotion for feeding and habitat use. Neotropical geophagine cichlids represent a newly identified adaptive radiation and provide a useful system for studying patterns of locomotor diversification and the implications of selective constraints on phenotypic divergence in general. We use multivariate ordination, models of phenotypic evolution and posterior predictive approaches to investigate the macroevolutionary adaptive landscape and test for evidence of early divergence of locomotor phenotypes in Geophagini. The evolution of locomotor phenotypes was characterized by selection towards at least two distinct adaptive peaks and the early divergence of modern morphological disparity. One adaptive peak included the benthic and epibenthic invertivores and was characterized by fishes with deep, laterally compressed bodies that optimize precise, slow-swimming manoeuvres. The second adaptive peak resulted from a shift in adaptive optima in the species-rich ram-feeding/rheophilic Crenicichla-Teleocichla clade and was characterized by species with streamlined bodies that optimize fast starts and rapid manoeuvres. Evolutionary models and posterior predictive approaches favoured an early shift to a new adaptive peak over decreasing rates of evolution as the underlying process driving the early divergence of locomotor phenotypes. The influence of multiple adaptive peaks on the divergence of locomotor phenotypes in Geophagini is compatible with the expectations of an ecologically driven

Evolutionary history of the Lake Tanganyika cichlid tribe Lamprologini (Teleostei: Perciformes) derived from mitochondrial and nuclear DNA data

OpenAIRE

Sturmbauer, Christian; Salzburger, Walter; Duftner, Nina; Schelly, Robert; Koblmueller, Stephan

2010-01-01

Lake Tanganyika comprises a cichlid species flock with substrate-breeding and mouthbrooding lineages. While sexual selection via mate choice on male mating color is thought to boost speciation rates in mouthbrooding cichlids, this is not the case in substrate-breeding lamprologines, which mostly form stable pairs and lack sexual dichromatism. We present a comprehensive reconstruction of the evolution of the cichlid tribe Lamprologini, based upon mtDNA sequences and multilocus nuclear DNA (AFL...

THE BEHAVIOUR AND BRAIN FUNCTION OF THE CICHLID FISH ...

African Journals Online (AJOL)

male and female conspecifics on a visual basis. ... Brain Function, Teleost, telencephalon, Cichlid fish behaviour, limbic system, hippocampus. ...... The effects of forebrain ablations on the behaviour of H. philander cannot be satisfactorily.

The effect of light intensity on prey detection behavior in two Lake Malawi cichlids, Aulonocara stuartgranti and Tramitichromis sp.

Science.gov (United States)

Schwalbe, Margot A B; Webb, Jacqueline F

2015-04-01

Two sand-dwelling cichlids from Lake Malawi (Aulonocara stuartgranti, Tramitichromis sp.) that feed on benthic invertebrates, but have different lateral line phenotypes, use lateral line and/or visual cues to detect prey under light versus dark conditions. The current study examined how ecologically relevant variation in light intensity [0-800 lux (lx)] influences detection of prey (mobile, immobile) in each species by analyzing six behavioral parameters. Both species fed at light intensities ≥1 lx and trends in behavior among light intensities were informative. However, prey type and/or time of day (but not light intensity) predicted all four parameters analyzed with generalized linear mixed models in A. stuartgranti, whereas the interaction of light intensity and time of day predicted three of these parameters in Tramitichromis sp. Data suggest that the critical light intensity is 1-12 lx for both species, that the integration of visual and lateral line input explains differences in detection of mobile and immobile prey and behavioral changes at the transition from 1 to 0 lx in A. stuartgranti, and that Tramitichromis sp. likely uses binocular vision to locate prey. Differences in the sensory biology of species that exploit similar prey will have important implications for the trophic ecology of African cichlid fishes.

A three-dimensional stereotaxic MRI brain atlas of the cichlid fish Oreochromis mossambicus.

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Simões, José M; Teles, Magda C; Oliveira, Rui F; Van der Linden, Annemie; Verhoye, Marleen

2012-01-01

The African cichlid Oreochromis mossambicus (Mozambique tilapia) has been used as a model system in a wide range of behavioural and neurobiological studies. The increasing number of genetic tools available for this species, together with the emerging interest in its use for neurobiological studies, increased the need for an accurate hodological mapping of the tilapia brain to supplement the available histological data. The goal of our study was to elaborate a three-dimensional, high-resolution digital atlas using magnetic resonance imaging, supported by Nissl staining. Resulting images were viewed and analysed in all orientations (transverse, sagittal, and horizontal) and manually labelled to reveal structures in the olfactory bulb, telencephalon, diencephalon, optic tectum, and cerebellum. This high resolution tilapia brain atlas is expected to become a very useful tool for neuroscientists using this fish model and will certainly expand their use in future studies regarding the central nervous system.

Parsing parallel evolution: ecological divergence and differential gene expression in the adaptive radiations of thick-lipped Midas cichlid fishes from Nicaragua.

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Manousaki, Tereza; Hull, Pincelli M; Kusche, Henrik; Machado-Schiaffino, Gonzalo; Franchini, Paolo; Harrod, Chris; Elmer, Kathryn R; Meyer, Axel

2013-02-01

The study of parallel evolution facilitates the discovery of common rules of diversification. Here, we examine the repeated evolution of thick lips in Midas cichlid fishes (the Amphilophus citrinellus species complex)-from two Great Lakes and two crater lakes in Nicaragua-to assess whether similar changes in ecology, phenotypic trophic traits and gene expression accompany parallel trait evolution. Using next-generation sequencing technology, we characterize transcriptome-wide differential gene expression in the lips of wild-caught sympatric thick- and thin-lipped cichlids from all four instances of repeated thick-lip evolution. Six genes (apolipoprotein D, myelin-associated glycoprotein precursor, four-and-a-half LIM domain protein 2, calpain-9, GTPase IMAP family member 8-like and one hypothetical protein) are significantly underexpressed in the thick-lipped morph across all four lakes. However, other aspects of lips' gene expression in sympatric morphs differ in a lake-specific pattern, including the magnitude of differentially expressed genes (97-510). Generally, fewer genes are differentially expressed among morphs in the younger crater lakes than in those from the older Great Lakes. Body shape, lower pharyngeal jaw size and shape, and stable isotopes (δ(13)C and δ(15)N) differ between all sympatric morphs, with the greatest differentiation in the Great Lake Nicaragua. Some ecological traits evolve in parallel (those related to foraging ecology; e.g. lip size, body and head shape) but others, somewhat surprisingly, do not (those related to diet and food processing; e.g. jaw size and shape, stable isotopes). Taken together, this case of parallelism among thick- and thin-lipped cichlids shows a mosaic pattern of parallel and nonparallel evolution. © 2012 Blackwell Publishing Ltd.

Body size diversity and frequency distributions of Neotropical cichlid fishes (Cichliformes: Cichlidae: Cichlinae.

Directory of Open Access Journals (Sweden)

Sarah E Steele

Full Text Available Body size is an important correlate of life history, ecology and distribution of species. Despite this, very little is known about body size evolution in fishes, particularly freshwater fishes of the Neotropics where species and body size diversity are relatively high. Phylogenetic history and body size data were used to explore body size frequency distributions in Neotropical cichlids, a broadly distributed and ecologically diverse group of fishes that is highly representative of body size diversity in Neotropical freshwater fishes. We test for divergence, phylogenetic autocorrelation and among-clade partitioning of body size space. Neotropical cichlids show low phylogenetic autocorrelation and divergence within and among taxonomic levels. Three distinct regions of body size space were identified from body size frequency distributions at various taxonomic levels corresponding to subclades of the most diverse tribe, Geophagini. These regions suggest that lineages may be evolving towards particular size optima that may be tied to specific ecological roles. The diversification of Geophagini appears to constrain the evolution of body size among other Neotropical cichlid lineages; non-Geophagini clades show lower species-richness in body size regions shared with Geophagini. Neotropical cichlid genera show less divergence and extreme body size than expected within and among tribes. Body size divergence among species may instead be present or linked to ecology at the community assembly scale.

Separated by sand, fused by dropping water: habitat barriers and fluctuating water levels steer the evolution of rock-dwelling cichlid populations in Lake Tanganyika.

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Koblmüller, Stephan; Salzburger, Walter; Obermüller, Beate; Eigner, Eva; Sturmbauer, Christian; Sefc, Kristina M

2011-06-01

The conditions of phenotypic and genetic population differentiation allow inferences about the evolution, preservation and loss of biological diversity. In Lake Tanganyika, water level fluctuations are assumed to have had a major impact on the evolution of stenotopic littoral species, though this hypothesis has not been specifically examined so far. The present study investigates whether subtly differentiated colour patterns of adjacent Tropheus moorii populations are maintained in isolation or in the face of continuous gene flow, and whether the presumed influence of water level fluctuations on lacustrine cichlids can be demonstrated in the small-scale population structure of the strictly stenotopic, littoral Tropheus. Distinct population differentiation was found even across short geographic distances and minor habitat barriers. Population splitting chronology and demographic histories comply with our expectation of old and rather stable populations on steeper sloping shore, and more recently established populations in a shallower region. Moreover, population expansions seem to coincide with lake level rises in the wake of Late Pleistocene megadroughts ~100 KYA. The imprint of hydrologic events on current population structure in the absence of ongoing gene flow suggests that phenotypic differentiation among proximate Tropheus populations evolves and persists in genetic isolation. Sporadic gene flow is effected by lake level fluctuations following climate changes and controlled by the persistence of habitat barriers during lake level changes. Since similar demographic patterns were previously reported for Lake Malawi cichlids, our data furthermore strengthen the hypothesis that major climatic events synchronized facets of cichlid evolution across the East African Great Lakes. © 2011 Blackwell Publishing Ltd.

Duration of memory of dominance relationships in a group living cichlid

Science.gov (United States)

Hotta, Takashi; Takeyama, Tomohiro; Jordan, Lyndon Alexander; Kohda, Masanori

2014-09-01

Animal contests are costly and tend to escalate when rivals have similar competitive abilities. Individuals that remember dominance relationships with rivals may avoid repeated agonistic interactions and hence avoid the costs of repeated escalation of contests. However, it can be difficult to experimentally disentangle the effects of memory from those of loser effects (losers behaving subordinately due to prior defeats). Here, we test whether loser effects or individual memory mediate contest behaviour in the African cichlid, Julidochromis transcriptus. We find that on days 3 and 5 after initial contests, losers display subordinate behaviour to contest winners but not to novel contestants. However, this effect disappears after 7 days, at which time losers do not display subordinate behaviour to either rival. These results show that (1) this fish can recall a previously dominant contestant for up to 5 days and (2) as no subordinate displays were shown to the novel contestant, there are no evidences for loser effects in this species. Such short-term memory of past interactions may have broad significance in social species with repeated interactions.

BioCichlid: central dogma-based 3D visualization system of time-course microarray data on a hierarchical biological network.

Science.gov (United States)

Ishiwata, Ryosuke R; Morioka, Masaki S; Ogishima, Soichi; Tanaka, Hiroshi

2009-02-15

BioCichlid is a 3D visualization system of time-course microarray data on molecular networks, aiming at interpretation of gene expression data by transcriptional relationships based on the central dogma with physical and genetic interactions. BioCichlid visualizes both physical (protein) and genetic (regulatory) network layers, and provides animation of time-course gene expression data on the genetic network layer. Transcriptional regulations are represented to bridge the physical network (transcription factors) and genetic network (regulated genes) layers, thus integrating promoter analysis into the pathway mapping. BioCichlid enhances the interpretation of microarray data and allows for revealing the underlying mechanisms causing differential gene expressions. BioCichlid is freely available and can be accessed at http://newton.tmd.ac.jp/. Source codes for both biocichlid server and client are also available.

The South African Forum for Radiation Protection

International Nuclear Information System (INIS)

Basson, J.K.; Le Roux, P.R.

1993-01-01

The use of ionising radiation in South Africa since the turn of the century was initially limited to x-rays and radium, with predominant applications in medicine for diagnosis and therapy. Since 1948 artificial radio-isotopes have been increasingly available and such applications have been widely extended to industry, agriculture and science. Initially, the Council for Scientific and Industrial Research developed radiation protection in South Africa. It was later recommended that an independent forum, the South African Forum for Radiation Protection, be established. The activities of the Forum are described

A high-resolution map of the Nile tilapia genome: a resource for studying cichlids and other percomorphs

Science.gov (United States)

2012-01-01

Background The Nile tilapia (Oreochromis niloticus) is the second most farmed fish species worldwide. It is also an important model for studies of fish physiology, particularly because of its broad tolerance to an array of environments. It is a good model to study evolutionary mechanisms in vertebrates, because of its close relationship to haplochromine cichlids, which have undergone rapid speciation in East Africa. The existing genomic resources for Nile tilapia include a genetic map, BAC end sequences and ESTs, but comparative genome analysis and maps of quantitative trait loci (QTL) are still limited. Results We have constructed a high-resolution radiation hybrid (RH) panel for the Nile tilapia and genotyped 1358 markers consisting of 850 genes, 82 markers corresponding to BAC end sequences, 154 microsatellites and 272 single nucleotide polymorphisms (SNPs). From these, 1296 markers could be associated in 81 RH groups, while 62 were not linked. The total size of the RH map is 34,084 cR3500 and 937,310 kb. It covers 88% of the entire genome with an estimated inter-marker distance of 742 Kb. Mapping of microsatellites enabled integration to the genetic map. We have merged LG8 and LG24 into a single linkage group, and confirmed that LG16-LG21 are also merged. The orientation and association of RH groups to each chromosome and LG was confirmed by chromosomal in situ hybridizations (FISH) of 55 BACs. Fifty RH groups were localized on the 22 chromosomes while 31 remained small orphan groups. Synteny relationships were determined between Nile tilapia, stickleback, medaka and pufferfish. Conclusion The RH map and associated FISH map provide a valuable gene-ordered resource for gene mapping and QTL studies. All genetic linkage groups with their corresponding RH groups now have a corresponding chromosome which can be identified in the karyotype. Placement of conserved segments indicated that multiple inter-chromosomal rearrangements have occurred between Nile tilapia

Nuclear markers reveal that inter-lake cichlids' similar morphologies do not reflect similar genealogy.

Science.gov (United States)

Kassam, Daud; Seki, Shingo; Horic, Michio; Yamaoka, Kosaku

2006-08-01

The apparent inter-lake morphological similarity among East African Great Lakes' cichlid species/genera has left evolutionary biologists asking whether such similarity is due to sharing of common ancestor or mere convergent evolution. In order to answer such question, we first used Geometric Morphometrics, GM, to quantify morphological similarity and then subsequently used Amplified Fragment Length Polymorphism, AFLP, to determine if similar morphologies imply shared ancestry or convergent evolution. GM revealed that not all presumed morphological similar pairs were indeed similar, and the dendrogram generated from AFLP data indicated distinct clusters corresponding to each lake and not inter-lake morphological similar pairs. Such results imply that the morphological similarity is due to convergent evolution and not shared ancestry. The congruency of GM and AFLP generated dendrograms imply that GM is capable of picking up phylogenetic signal, and thus GM can be potential tool in phylogenetic systematics.

[Feeding habits of cichlid species (Perciformes: Cichlidae) in Caobas lake, Quintana Roo, Mexico].

Science.gov (United States)

Valtierra-Vega, M T; Schmitter-Soto, J J

2000-01-01

Feeding habits of seven cichlid species (Archocentrus octofasciatus, A. spilurus, "Cichlasoma" robertsoni, "C." synspilum, "C." urophthalmus, Petenia splendida, Thorichthys meeki) in Lake Caobas, southern Yucatan Peninsula, were studied. Samples were taken with enclosure and cast nets during the dry and rainy seasons of 1995 (day and night). The environment was characterized by measuring temperature, conductivity and pH. All individuals were below 41 mm SL (N = 281). Frequency of occurrence and prey abundance were analyzed. Main prey items were chironomids, mites, copepods, cladocerans, and ostracods. The cichlids fed mainly on zooplankton, with the partial exceptions of P. splendida (piscivore), "C." synspilum and A. spilurus (herbivores). A cluster analysis showed that the most similar trophic spectra were those of T. meeki, "C." robertsoni and "C." salvini, which were also the least diverse. "C." synspilum and A. spilurus had an intermediate distance between their diets and those of other species. The species with the most distinctive feeding composition were P. splendida (with the most diverse and equitable diet) and the omnivore A. octofasciatus (whose diet was the richest one). T. meeki showed quantitative diel, ontogenetic, and seasonal diet changes, but none between sexes. "C." robertsoni, "C." salvini and "C." synspilum differ in food habits in Caobas and in other localities, a fact that underscores the trophic adaptability of cichlids. Trophic overlap between cichlids in Caobas could imply absence of competition, perhaps because resources are abundant in the ecosystem.

The behaviour and brain function of the Cichlid fish ...

African Journals Online (AJOL)

... the teleost forebrain houses a primitive limbic system the main functions of which would be general arousal and the selection of appropriate responses to the incoming external and endogenous (motivational) stimuli. Keywords: Brain Function, Teleost, telencephalon, Cichlid fish behaviour, limbic system, hippocampus ...

Mechanisms of rapid sympatric speciation by sex reversal and sexual selection in cichlid fish.

Science.gov (United States)

Lande, R; Seehausen, O; van Alphen, J J

2001-01-01

Mechanisms of speciation in cichlid fish were investigated by analyzing population genetic models of sexual selection on sex-determining genes associated with color polymorphisms. The models are based on a combination of laboratory experiments and field observations on the ecology, male and female mating behavior, and inheritance of sex-determination and color polymorphisms. The models explain why sex-reversal genes that change males into females tend to be X-linked and associated with novel colors, using the hypothesis of restricted recombination on the sex chromosomes, as suggested by previous theory on the evolution of recombination. The models reveal multiple pathways for rapid sympatric speciation through the origin of novel color morphs with strong assortative mating that incorporate both sex-reversal and suppressor genes. Despite the lack of geographic isolation or ecological differentiation, the new species coexists with the ancestral species either temporarily or indefinitely. These results may help to explain different patterns and rates of speciation among groups of cichlids, in particular the explosive diversification of rock-dwelling haplochromine cichlids.

Mutational changes of intraspecific agressiveness in the convict cichlid (Cichlasoma nigrofasciatum Guenther) after irradiation of parental spermatogonia and oogonia with different doses of X-rays

International Nuclear Information System (INIS)

Juerges, U.; Schroeder, J.H.; Sund, M.

1984-01-01

The agonistic behavior of mated convict cichlids (Cichlasoma nigrofasciatum) derived from gonial germ cells which were exposed to 0 (controls), 250, 500, 1,000, or 2,000 R of X-rays was determined by counting the attacks delivered to subadult conspecifics during the first eight days after spawning. While no day effects and no interactions with sex and radiation dose were found, males were significantly more aggressive in the treatment groups than the corresponding females. The highest aggressivness appeared in F 1 pairs derived from parental gonia irradiated with 250 R, and the lowest aggressiveness occurred in the 500-F 1 group. These two treatment groups differed significantly from each other, whereas no further significant differences could be detected. F 1 males derived from gonial X-irradiation with 750 R could not be mated successfully because they killed their own females. The changes of male aggressiveness reflect reversely the previously published results of changes in social cohesiveness of the individual cichlid fish. (author)

Reticulate phylogeny of gastropod-shell-breeding cichlids from Lake Tanganyika – the result of repeated introgressive hybridization

Directory of Open Access Journals (Sweden)

Blanc Michel

2007-01-01

Full Text Available Abstract Background The tribe Lamprologini is the major substrate breeding lineage of Lake Tanganyika's cichlid species flock. Among several different life history strategies found in lamprologines, the adaptation to live and breed in empty gastropod shells is probably the most peculiar. Although shell-breeding arose several times in the evolutionary history of the lamprologines, all obligatory and most facultative shell-breeders belong to the so called "ossified group", a monophyletic lineage within the lamprologine cichlids. Since their distinctive life style enables these species to live and breed in closest vicinity, we hypothesized that these cichlids might be particularly prone to accidental hybridization, and that introgression might have affected the evolutionary history of this cichlid lineage. Results Our analyses revealed discrepancies between phylogenetic hypotheses based on mitochondrial and nuclear (AFLP data. While the nuclear phylogeny was congruent with morphological, behavioral and ecological characteristics, several species – usually highly specialized shell-breeders – were placed at contradicting positions in the mitochondrial phylogeny. The discordant phylogenies strongly suggest repeated incidents of introgressive hybridization between several distantly related shell-breeding species, which reticulated the phylogeny of this group of cichlids. Long interior branches and high bootstrap support for many interior nodes in the mitochondrial phylogeny argue against a major effect of ancient incomplete lineage sorting on the phylogenetic reconstruction. Moreover, we provide morphological and genetic (mtDNA and microsatellites evidence for ongoing hybridization among distantly related shell-breeders. In these cases, the territorial males of the inferred paternal species are too large to enter the shells of their mate, such that they have to release their sperm over the entrance of the shell to fertilize the eggs. With sperm

Not a simple case - A first comprehensive phylogenetic hypothesis for the Midas cichlid complex in Nicaragua (Teleostei: Cichlidae: Amphilophus).

Science.gov (United States)

Geiger, Matthias F; McCrary, Jeffrey K; Schliewen, Ulrich K

2010-09-01

Nicaraguan Midas cichlids from crater lakes have recently attracted attention as potential model systems for speciation research, but no attempt has been made to comprehensively reconstruct phylogenetic relationships of this highly diverse and recently evolved species complex. We present a first AFLP (2793 loci) and mtDNA based phylogenetic hypothesis including all described and several undescribed species from six crater lakes (Apoyeque, Apoyo, Asososca Leon, Masaya, Tiscapa and Xiloá), the two great Lakes Managua and Nicaragua and the San Juan River. Our analyses demonstrate that the relationships between the Midas cichlid members are complex, and that phylogenetic information from different markers and methods do not always yield congruent results. Nevertheless, monophyly support for crater lake assemblages from Lakes Apoyeque, Apoyo, A. Leon is high as compared to those from L. Xiloá indicating occurrence of sympatric speciation. Further, we demonstrate that a 'three species' concept for the Midas cichlid complex is inapplicable and consequently that an individualized and voucher based approach in speciation research of the Midas cichlid complex is necessary at least as long as there is no comprehensive revision of the species complex available. Copyright 2010 Elsevier Inc. All rights reserved.

A novel molecular marker for the study of Neotropical cichlid phylogeny.

Science.gov (United States)

Fabrin, T M C; Gasques, L S; Prioli, S M A P; Prioli, A J

2015-12-22

The use of molecular markers has contributed to phylogeny and to the reconstruction of species' evolutionary history. Each region of the genome has different evolution rates, which may or may not identify phylogenetic signal at different levels. Therefore, it is important to assess new molecular markers that can be used for phylogenetic reconstruction. Regions that may be associated with species characteristics and are subject to selective pressure, such as opsin genes, which encode proteins related to the visual system and are widely expressed by Cichlidae family members, are interesting. Our aim was to identify a new nuclear molecular marker that could establish the phylogeny of Neotropical cichlids and is potentially correlated with the visual system. We used Bayesian inference and maximum likelihood analysis to support the use of the nuclear opsin LWS gene in the phylogeny of eight Neotropical cichlid species. Their use concatenated to the mitochondrial gene COI was also tested. The LWS gene fragment comprised the exon 2-4 region, including the introns. The LWS gene provided good support for both analyses up to the genus level, distinguishing the studied species, and when concatenated to the COI gene, there was a good support up to the species level. Another benefit of utilizing this region, is that some polymorphisms are associated with changes in spectral properties of the LWS opsin protein, which constitutes the visual pigment that absorbs red light. Thus, utilization of this gene as a molecular marker to study the phylogeny of Neotropical cichlids is promising.

Evolution of opercle shape in cichlid fishes from Lake Tanganyika - adaptive trait interactions in extant and extinct species flocks.

Science.gov (United States)

Wilson, Laura A B; Colombo, Marco; Sánchez-Villagra, Marcelo R; Salzburger, Walter

2015-11-20

Phenotype-environment correlations and the evolution of trait interactions in adaptive radiations have been widely studied to gain insight into the dynamics underpinning rapid species diversification. In this study we explore the phenotype-environment correlation and evolution of operculum shape in cichlid fishes using an outline-based geometric morphometric approach combined with stable isotope indicators of macrohabitat and trophic niche. We then apply our method to a sample of extinct saurichthyid fishes, a highly diverse and near globally distributed group of actinopterygians occurring throughout the Triassic, to assess the utility of extant data to inform our understanding of ecomorphological evolution in extinct species flocks. A series of comparative methods were used to analyze shape data for 54 extant species of cichlids (N = 416), and 6 extinct species of saurichthyids (N = 44). Results provide evidence for a relationship between operculum shape and feeding ecology, a concentration in shape evolution towards present along with evidence for convergence in form, and significant correlation between the major axes of shape change and measures of gut length and body elongation. The operculum is one of few features that can be compared in extant and extinct groups, enabling reconstruction of phenotype-environment interactions and modes of evolutionary diversification in deep time.

Morphology, molecules, and monogenean parasites: an example of an integrative approach to cichlid biodiversity.

Directory of Open Access Journals (Sweden)

Maarten Van Steenberge

Full Text Available The unparalleled biodiversity of Lake Tanganyika (Africa has fascinated biologists for over a century; its unique cichlid communities are a preferred model for evolutionary research. Although species delineation is, in most cases, relatively straightforward, higher-order classifications were shown not to agree with monophyletic groups. Here, traditional morphological methods meet their limitations. A typical example are the tropheine cichlids currently belonging to Simochromis and Pseudosimochromis. The affiliations of these widespread and abundant cichlids are poorly understood. Molecular work suggested that genus and species boundaries should be revised. Moreover, previous morphological results indicated that intraspecific variation should be considered to delineate species in Lake Tanganyika cichlids. We review the genera Simochromis and Pseudosimochromis using an integrative approach. Besides a morphometric study and a barcoding approach, monogenean Cichlidogyrus (Platyhelminthes: Ancyrocephalidae gill parasites, often highly species-specific, are used as complementary markers. Six new species are described. Cichlidogyrus raeymaekersi sp. nov., C. muterezii sp. nov. and C. banyankimbonai sp. nov. infect S. diagramma. Cichlidogyrus georgesmertensi sp. nov. was found on S. babaulti and S. pleurospilus, C. franswittei sp. nov. on both S. marginatus and P. curvifrons and C. frankwillemsi sp. nov. only on P. curvifrons. As relatedness between Cichlidogyrus species usually reflects relatedness between hosts, we considered Simochromis monotypic because the three Cichlidogyrus species found on S. diagramma belonged to a different morphotype than those found on the other Simochromis. The transfer of S. babaulti, S. marginatus, S. pleurospilus and S. margaretae to Pseudosimochromis was justified by the similarity of their Cichlidogyrus fauna and the intermediate morphology of S. margaretae. Finally parasite data also supported the synonymy between S

Aggression and welfare in a common aquarium fish, the Midas cichlid.

Science.gov (United States)

Oldfield, Ronald G

2011-01-01

Many species of fishes are aggressive when placed in small aquaria. Aggression can negatively affect the welfare of those individuals toward whom it is directed. Animals may behave aggressively in order to defend resources such as food, shelter, mates, and offspring. The decision to defend depends on the distribution of resources and on ecological factors such as number of competitors, amount of available space, and amount of habitat complexity. This study tested the effects of these factors on aggression in a common aquarium fish, the Midas cichlid (Amphilophus citrinellus). The study found that time spent behaving aggressively was not associated with small-scale differences in group size or available space. Aggression was significantly lower in a large aquarium with a complex habitat. Aquaria of sizes typically used in the companion animal (pet) hobby did not provide optimal welfare for cichlids housed with aggressive conspecifics. The public should be aware that this and similar species require larger aquaria with complex habitat, which elicit more natural behavior.

Magadi tilapia ecological specialization: filling the early gap in the speciation continuum.

Science.gov (United States)

Pinho, Catarina; Faria, Rui

2016-04-01

Cichlid fish are well known for their high speciation rates, which are usually accompanied by spectacular and rapid diversification in eco-morphological and secondary sexual traits. This is best illustrated by the famous repeated explosive radiations in the African Great Lakes Tanganyika, Malawi and Victoria, each lake harbouring several hundreds of mostly endemic species. Correspondingly, cichlids diversified very rapidly in many other lakes across their range. Although the larger radiations, unparalleled in vertebrates, are certainly the most intriguing, they are also the most intricate and difficult to address because of their complex nature. This is where smaller, simpler systems may prove to be the most useful. In this issue of Molecular Ecology, Kavembe et al. (2016) report very recent genetic diversification accompanied by ecological specialization in cichlids of the small and ecologically extreme Lake Magadi, in Kenya. Combining geometric morphometrics, stable isotope analysis, population genomics using RADSeq data and coalescent-based modelling techniques, the authors characterize the eco-morphological differences between genetically distinct populations of Magadi tilapia (Alcolapia grahami), which are consistent with the different environmental conditions they experience, and infer their history of divergence. The simplicity of the focal system and the use of a multidisciplinary approach make this work particularly important for our understanding of the early stages of speciation, in both cichlids and other organisms. © 2016 John Wiley & Sons Ltd.

Genetic Evidence for Multiple Sources of the Non-Native Fish Cichlasoma urophthalmus (Günther; Mayan Cichlids) in Southern Florida

OpenAIRE

Harrison, Elizabeth; Trexler, Joel C.; Collins, Timothy M.; Vazquez-Domínguez, Ella; Razo-Mendivil, Ulises; Matamoros, Wilfredo A.; Barrientos, Christian

2014-01-01

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids...

Rapid sympatric ecological differentiation of crater lake cichlid fishes within historic times

Directory of Open Access Journals (Sweden)

Harrod Chris

2010-05-01

Full Text Available Abstract Background After a volcano erupts, a lake may form in the cooled crater and become an isolated aquatic ecosystem. This makes fishes in crater lakes informative for understanding sympatric evolution and ecological diversification in barren environments. From a geological and limnological perspective, such research offers insight about the process of crater lake ecosystem establishment and speciation. In the present study we use genetic and coalescence approaches to infer the colonization history of Midas cichlid fishes (Amphilophus cf. citrinellus that inhabit a very young crater lake in Nicaragua-the ca. 1800 year-old Lake Apoyeque. This lake holds two sympatric, endemic morphs of Midas cichlid: one with large, hypertrophied lips (~20% of the total population and another with thin lips. Here we test the associated ecological, morphological and genetic diversification of these two morphs and their potential to represent incipient speciation. Results Gene coalescence analyses [11 microsatellite loci and mitochondrial DNA (mtDNA sequences] suggest that crater lake Apoyeque was colonized in a single event from the large neighbouring great lake Managua only about 100 years ago. This founding in historic times is also reflected in the extremely low nuclear and mitochondrial genetic diversity in Apoyeque. We found that sympatric adult thin- and thick-lipped fishes occupy distinct ecological trophic niches. Diet, body shape, head width, pharyngeal jaw size and shape and stable isotope values all differ significantly between the two lip-morphs. The eco-morphological features pharyngeal jaw shape, body shape, stomach contents and stable isotopes (δ15N all show a bimodal distribution of traits, which is compatible with the expectations of an initial stage of ecological speciation under disruptive selection. Genetic differentiation between the thin- and thick-lipped population is weak at mtDNA sequence (FST = 0.018 and absent at nuclear

Phylogenetic relationships among East African haplochromine fish as revealed by short interspersed elements (SINEs).

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Terai, Yohey; Takezaki, Naoko; Mayer, Werner E; Tichy, Herbert; Takahata, Naoyuki; Klein, Jan; Okada, Norihiro

2004-01-01

Genomic DNA libraries were prepared from two endemic species of Lake Victoria haplochromine (cichlid) fish and used to isolate and characterize a set of short interspersed elements (SINEs). The distribution and sequences of the SINEs were used to infer phylogenetic relationships among East African haplochromines. The SINE-based classification divides the fish into four groups, which, in order of their divergence from a stem lineage, are the endemic Lake Tanganyika flock (group 1); fish of the nonendemic, monotypic, widely distributed genus Astatoreochromis (group 2); the endemic Lake Malawi flock (group 3); and group 4, which contains fish from widely dispersed East African localities including Lakes Victoria, Edward, George, Albert, and Rukwa, as well as many rivers. The group 4 haplochromines are characterized by a subset of polymorphic SINEs, each of which is present in some individuals and absent in others of the same population at a given locality, the same morphologically defined species, and the same mtDNA-defined haplogroup. SINE-defined group 4 contains six of the seven previously described mtDNA haplogroups. One of the polymorphic SINEs appears to be fixed in the endemic Lake Victoria flock; four others display the presence-or-absence polymorphism within the species of this flock. These findings have implications for the origin of Lake Victoria cichlids and for their founding population sizes.

Complete mitochondrial DNA sequences of the Victoria tilapia (Oreochromis variabilis) and Redbelly Tilapia (Tilapia zilli): genome characterization and phylogeny analysis.

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Kinaro, Zachary Omambia; Xue, Liangyi; Volatiana, Josies Ancella

2016-07-01

The Cichlid fishes have played an important role in evolutionary biology, population studies and aquaculture industry with East African species representing a model suited for studying adaptive radiation and speciation for cichlid genome projects in which closely related genomes are fast emerging presenting questions on phenotype-genotype relations. The complete mitochondrial genomes presented here are for two closely related but eco-morphologically distinct Lake Victoria basin cichlids, Oreochromis variabilis, an endangered native species and Tilapia zilli, an invasive species, both of which are important economic fishes in local areas. The complete mitochondrial genomes determined for O. variabilis and T. zilli are 16 626 and 16,619 bp, respectively. Both the mitogenomes contain 13 protein-coding genes, 22 tRNAs, 2 rRNAs and a non-coding control region, which are typical of vertebrate mitogenomes. Phylogenetic analyses of the two species revealed that though both lie within family Cichlidae, they are remotely related.

Genetic evidence for multiple sources of the non-native fish Cichlasoma urophthalmus (Günther; Mayan Cichlids in southern Florida.

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Elizabeth Harrison

Full Text Available The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid. Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype. Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7-8 generations after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions.

Genetic evidence for multiple sources of the non-native fish Cichlasoma urophthalmus (Günther; Mayan Cichlids) in southern Florida.

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Harrison, Elizabeth; Trexler, Joel C; Collins, Timothy M; Vazquez-Domínguez, Ella; Razo-Mendivil, Ulises; Matamoros, Wilfredo A; Barrientos, Christian

2014-01-01

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7-8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions.

Divergent mating preferences and nuptial coloration in sibling species of cichlid fish

NARCIS (Netherlands)

Sluijs, Inke van der

2008-01-01

Mate choice by female cichlid fish from Lake Victoria plays an important role in speciation and the maintenance of species. Females are expected to select against males that are intermediate in their phenotype during the process of speciation driven by sexual selection. To test this, we hybridized

Rapid adaptation to a novel light environment: The importance of ontogeny and phenotypic plasticity in shaping the visual system of Nicaraguan Midas cichlid fish (Amphilophus citrinellus spp.).

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Härer, Andreas; Torres-Dowdall, Julián; Meyer, Axel

2017-10-01

Colonization of novel habitats is typically challenging to organisms. In the initial stage after colonization, approximation to fitness optima in the new environment can occur by selection acting on standing genetic variation, modification of developmental patterns or phenotypic plasticity. Midas cichlids have recently colonized crater Lake Apoyo from great Lake Nicaragua. The photic environment of crater Lake Apoyo is shifted towards shorter wavelengths compared to great Lake Nicaragua and Midas cichlids from both lakes differ in visual sensitivity. We investigated the contribution of ontogeny and phenotypic plasticity in shaping the visual system of Midas cichlids after colonizing this novel photic environment. To this end, we measured cone opsin expression both during development and after experimental exposure to different light treatments. Midas cichlids from both lakes undergo ontogenetic changes in cone opsin expression, but visual sensitivity is consistently shifted towards shorter wavelengths in crater lake fish, which leads to a paedomorphic retention of their visual phenotype. This shift might be mediated by lower levels of thyroid hormone in crater lake Midas cichlids (measured indirectly as dio2 and dio3 gene expression). Exposing fish to different light treatments revealed that cone opsin expression is phenotypically plastic in both species during early development, with short and long wavelength light slowing or accelerating ontogenetic changes, respectively. Notably, this plastic response was maintained into adulthood only in the derived crater lake Midas cichlids. We conclude that the rapid evolution of Midas cichlids' visual system after colonizing crater Lake Apoyo was mediated by a shift in visual sensitivity during ontogeny and was further aided by phenotypic plasticity during development. © 2017 John Wiley & Sons Ltd.

Parental Investment and sexual immune dimorphism in cichlids ans syngnathids

OpenAIRE

Keller, Isabel Salome

2017-01-01

I investigated how the interrelationship between parental investment and sexual immune dimorphism shape the evolution of parental care strategies within the cichlids and syngnathids. To understand why parental investment is displayed in such diversity in the animal kingdom, I assessed evolutionary and provisioning costs of parental investment in male pregnancy, biparental and maternal mouthbrooding. Additionally, to address the importance of parental investment, I tested for maternal effects ...

Allometric shape change of the lower pharyngeal jaw correlates with a dietary shift to piscivory in a cichlid fish

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Hellig, Christoph J.; Kerschbaumer, Michaela; Sefc, Kristina M.; Koblmüller, Stephan

2010-07-01

The morphological versatility of the pharyngeal jaw of cichlid fishes is assumed to represent a key factor facilitating their unparalleled trophic diversification and explosive radiation. It is generally believed that the functional design of an organism relates to its ecology, and thus, specializations to different diets are typically associated with distinct morphological designs, especially manifested in the cichlids’ pharyngeal jaw apparatus. Thereby, the lower pharyngeal jaw (LPJ) incorporates some of the most predictive features for distinct diet-related morphotypes. Thus, considering that piscivorous cichlids experience an ontogenetic dietary shift from typically various kinds of invertebrates to fish, concomitant morphological changes in the LPJ are expected. Using Lepidiolamprologus elongatus, a top predator in the shallow rocky habitat of Lake Tanganyika, as model, and applying geometric and traditional morphometric techniques, we demonstrate an allometric change in ontogenetic LPJ shape development coinciding with the completion of the dietary shift toward piscivory. The piscivorous LPJ morphotype is initiated in juvenile fish by increasing elongation and narrowing of the LPJ and—when the fish reach a size of 80-90 mm standard length—further refined by the elongation of the posterior muscular processes, which serve as insertion for the fourth musculus levator externus. The enlarged muscular processes of the fully mature piscivorous morphotype provide for the construction of a powerful lever system, which allows the large individuals to process large prey fish and rely on exclusive piscivory.

Complementary description of Ergasilus arthrosis Roberts, 1969 (Copepoda: Poecilostomatoida: Ergasilidae), a new parasite of cichlid teleosts in southeast Mexico.

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Jiménez-García, María Isabel; Suárez-Morales, Eduardo

2017-01-01

During a parasitological survey of the ichthyofauna of Lake Catemaco, a freshwater system in the Mexican State of Veracruz, the widespread copepod Ergasilus arthrosis Roberts, 1969 was recovered from two cichlid teleosts, Mayaheros urophthalmus (Günther) and Oreochromis sp. This is the first confirmed record of this copepod species outside of the United States and from Mexico; its finding as a parasite of cichlids represents an expansion of the known host range for this copepod. The local prevalence and intensity of infection of E. arthrosis was highest in M. urophthalmus. The infection prevalence of E. arthrosis on M. urophthalmus (60%) was higher than that known for other ergasilids on cichlids. Ergasilus arthrosis can be distinguished from its closest congener E. lizae Krøyer, 1863 by the morphometry of the antennary segments, the ventral ornamentation of the thoracic sclerites and by details of the antennulary setation, but also by its habitat and host preferences. Taxonomic illustrations and morphological details of the specimens examined are also provided together with comments on the variability of this species.

Testing the carotenoid trade-off hypothesis in the polychromatic Midas cichlid, Amphilophus citrinellus.

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Lin, Susan M; Nieves-Puigdoller, Katherine; Brown, Alexandria C; McGraw, Kevin J; Clotfelter, Ethan D

2010-01-01

Many animals use carotenoid pigments derived from their diet for coloration and immunity. The carotenoid trade-off hypothesis predicts that, under conditions of carotenoid scarcity, individuals may be forced to allocate limited carotenoids to either coloration or immunity. In polychromatic species, the pattern of allocation may differ among individuals. We tested the carotenoid trade-off hypothesis in the Midas cichlid, Amphilophus citrinellus, a species with two ontogenetic color morphs, barred and gold, the latter of which is the result of carotenoid expression. We performed a diet-supplementation experiment in which cichlids of both color morphs were assigned to one of two diet treatments that differed only in carotenoid content (beta-carotene, lutein, and zeaxanthin). We measured integument color using spectrometry, quantified carotenoid concentrations in tissue and plasma, and assessed innate immunity using lysozyme activity and alternative complement pathway assays. In both color morphs, dietary carotenoid supplementation elevated plasma carotenoid circulation but failed to affect skin coloration. Consistent with observable differences in integument coloration, we found that gold fish sequestered more carotenoids in skin tissue than barred fish, but barred fish had higher concentrations of carotenoids in plasma than gold fish. Neither measure of innate immunity differed between gold and barred fish, or as a function of dietary carotenoid supplementation. Lysozyme activity, but not complement activity, was strongly affected by body condition. Our data show that a diet low in carotenoids is sufficient to maintain both coloration and innate immunity in Midas cichlids. Our data also suggest that the developmental transition from the barred to gold morph is not accompanied by a decrease in innate immunity in this species.

Morphology and Efficiency of a Specialized Foraging Behavior, Sediment Sifting, in Neotropical Cichlid Fishes

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Willis, Stuart; Watkins, Crystal; Honeycutt, Rodney L.; Winemiller, Kirk O.

2014-01-01

Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny. PMID:24603485

Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

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Hernán López-Fernández

Full Text Available Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.

Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

Science.gov (United States)

López-Fernández, Hernán; Arbour, Jessica; Willis, Stuart; Watkins, Crystal; Honeycutt, Rodney L; Winemiller, Kirk O

2014-01-01

Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.

Evolution of body shape in differently coloured sympatric congeners and allopatric populations of Lake Malawi's rock-dwelling cichlids.

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Husemann, M; Tobler, M; McCauley, C; Ding, B; Danley, P D

2014-05-01

The cichlid fishes of Lake Malawi represent one of the most diverse adaptive radiations of vertebrates known. Among the rock-dwelling cichlids (mbuna), closely related sympatric congeners possess similar trophic morphologies (i.e. cranial and jaw structures), defend overlapping or adjacent territories, but can be easily distinguished based on male nuptial coloration. The apparent morphological similarity of congeners, however, leads to an ecological conundrum: theory predicts that ecological competition should lead to competitive exclusion. Hence, we hypothesized that slight, yet significant, ecological differences accompanied the divergence in sexual signals and that the divergence of ecological and sexual traits is correlated. To evaluate this hypothesis, we quantified body shape, a trait of known ecological importance, in populations of Maylandia zebra, a barred, widespread mbuna, and several sympatric nonbarred congeners. We found that the barred populations differ in body shape from their nonbarred sympatric congeners and that the direction of shape differences was consistent across all barred vs. nonbarred comparisons. Barred populations are generally deeper bodied which may be an adaptation to the structurally complex habitat they prefer, whereas the nonbarred species have a more fusiform body shape, which may be adaptive in their more open microhabitat. Furthermore, M. zebra populations sympatric with nonbarred congeners differ from populations where the nonbarred phenotype is absent and occupy less morphospace, indicating potential ecological character displacement. Mitochondrial DNA as well as published AFLP data indicated that the nonbarred populations are not monophyletic and therefore may have evolved multiple times independently. Overall our data suggest that the evolution of coloration and body shape may be coupled as a result of correlational selection. We hypothesize that correlated evolution of sexually selected and ecological traits may have

Discovery of the invasive Mayan Cichlid fish "Cichlasoma" urophthalmus (Günther 1862) in Thailand, with comments on other introductions and potential impacts

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Nico, Leo G.; Beamish, William H.; Musikasinthorn, Prachya

2007-01-01

We report on the occurrence and possible establishment of a non-native cichlid fish in a brackish-water system in the lower Chao Phraya River delta region, Thailand. Although, the possibility of some degree of introgressive hybridization can not be ruled out, Thailand specimens agree best with Mayan Cichlid “Cichlasoma” urophthalmus (Günther 1862). Our collections represent the first records of this New World, highly-invasive, euryhaline fish from Thailand and coincides with recent collections from Singapore. Positive identification of specimens as “C.” urophthalmus requires caution due to the diversity of the Cichlidae (>1,300 species), widespread introduction of many family members, variation within species, extensive interspecific overlap in characters, and proliferation of artificial cichlid hybrids (e.g., Flowerhorns). We first became aware of the Thailand population in 2005 when “C.” urophthalmus began appearing in the catches of local fishermen. We visited the site in November 2006 and obtained and examined voucher specimens. The abundance and wide size range of juveniles and adults in local ponds and an adjacent canal is evidence of natural reproduction. Because water bodies throughout the Chao Phraya delta are interconnected and subject to flooding, it is likely that “C.” urophthalmus is already established and is dispersing, but surveys and monitoring are needed to determine their exact geographic range. The Thailand population is compared to “C.” urophthalmus introduced into Florida (USA). Based on what is known about Florida “C.” urophthalmus, it is predicted that this cichlid will further invade coastal and inland waters in Thailand and elsewhere in Southeast Asia. This cichlid has a long history in the aquarium trade in Europe. However, there are no records from the wild in European waters and, because of the colder climate, the possibility of establishment in that region is relatively low.

The gut microbial community of Midas cichlid fish in repeatedly evolved limnetic-benthic species pairs.

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Franchini, Paolo; Fruciano, Carmelo; Frickey, Tancred; Jones, Julia C; Meyer, Axel

2014-01-01

Gut bacterial communities are now known to influence a range of fitness related aspects of organisms. But how different the microbial community is in closely related species, and if these differences can be interpreted as adaptive is still unclear. In this study we compared microbial communities in two sets of closely related sympatric crater lake cichlid fish species pairs that show similar adaptations along the limnetic-benthic axis. The gut microbial community composition differs in the species pair inhabiting the older of two crater lakes. One major difference, relative to other fish, is that in these cichlids that live in hypersaline crater lakes, the microbial community is largely made up of Oceanospirillales (52.28%) which are halotolerant or halophilic bacteria. This analysis opens up further avenues to identify candidate symbiotic or co-evolved bacteria playing a role in adaptation to similar diets and life-styles or even have a role in speciation. Future functional and phylosymbiotic analyses might help to address these issues.

Brain structure evolution in a basal vertebrate clade: evidence from phylogenetic comparative analysis of cichlid fishes

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Kolm Niclas

2009-09-01

Full Text Available Abstract Background The vertebrate brain is composed of several interconnected, functionally distinct structures and much debate has surrounded the basic question of how these structures evolve. On the one hand, according to the 'mosaic evolution hypothesis', because of the elevated metabolic cost of brain tissue, selection is expected to target specific structures mediating the cognitive abilities which are being favored. On the other hand, the 'concerted evolution hypothesis' argues that developmental constraints limit such mosaic evolution and instead the size of the entire brain varies in response to selection on any of its constituent parts. To date, analyses of these hypotheses of brain evolution have been limited to mammals and birds; excluding Actinopterygii, the basal and most diverse class of vertebrates. Using a combination of recently developed phylogenetic multivariate allometry analyses and comparative methods that can identify distinct rates of evolution, even in highly correlated traits, we studied brain structure evolution in a highly variable clade of ray-finned fishes; the Tanganyikan cichlids. Results Total brain size explained 86% of the variance in brain structure volume in cichlids, a lower proportion than what has previously been reported for mammals. Brain structures showed variation in pair-wise allometry suggesting some degree of independence in evolutionary changes in size. This result is supported by variation among structures on the strength of their loadings on the principal size axis of the allometric analysis. The rate of evolution analyses generally supported the results of the multivariate allometry analyses, showing variation among several structures in their evolutionary patterns. The olfactory bulbs and hypothalamus were found to evolve faster than other structures while the dorsal medulla presented the slowest evolutionary rate. Conclusion Our results favor a mosaic model of brain evolution, as certain

Molecular phylogeny and biogeography of the Neotropical cichlid fish tribe Cichlasomatini (Teleostei: Cichlidae: Cichlasomatinae)

Czech Academy of Sciences Publication Activity Database

Musilová, Zuzana; Říčan, Oldřich; Janko, Karel; Novák, J.

2008-01-01

Roč. 46, - (2008), s. 659-672 ISSN 1055-7903 R&D Projects: GA MŠk LC06073 Grant - others:GA UK(CZ) 182/2004/B-BIO; GA UK(CZ) 139407 Institutional research plan: CEZ:AV0Z50450515 Keywords : molecular phylogeny * Cichlids * south America Subject RIV: EG - Zoology Impact factor: 3.871, year: 2008

Demography and genome divergence of lake and stream populations of an East African cichlid fish.

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Egger, Bernd; Roesti, Marius; Böhne, Astrid; Roth, Olivia; Salzburger, Walter

2017-10-01

Disentangling the processes and mechanisms underlying adaptive diversification is facilitated by the comparative study of replicate population pairs that have diverged along a similar environmental gradient. Such a setting is realized in a cichlid fish from southern Lake Tanganyika, Astatotilapia burtoni, which occurs within the lake proper as well as in various affluent rivers. Previously, we demonstrated that independent lake and stream populations show similar adaptations to the two habitat regimes. However, little is known about the evolutionary and demographic history of the A. burtoni populations in question and the patterns of genome divergence among them. Here, we apply restriction site-associated DNA sequencing (RADseq) to examine the evolutionary history, the population structure and genomic differentiation of lake and stream populations in A. burtoni. A phylogenetic reconstruction based on genome-wide molecular data largely resolved the evolutionary relationships among populations, allowing us to re-evaluate the independence of replicate lake-stream population clusters. Further, we detected a strong pattern of isolation by distance, with baseline genomic divergence increasing with geographic distance and decreasing with the level of gene flow between lake and stream populations. Genome divergence patterns were heterogeneous and inconsistent among lake-stream population clusters, which is explained by differences in divergence times, levels of gene flow and local selection regimes. In line with the latter, we only detected consistent outlier loci when the most divergent lake-stream population pair was excluded. Several of the thus identified candidate genes have inferred functions in immune and neuronal systems and show differences in gene expression between lake and stream populations. © 2017 John Wiley & Sons Ltd.

Correlated evolution of body and fin morphology in the cichlid fishes.

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Feilich, Kara L

2016-10-01

Body and fin shapes are chief determinants of swimming performance in fishes. Different configurations of body and fin shapes can suit different locomotor specializations. The success of any configuration is dependent upon the hydrodynamic interactions between body and fins. Despite the importance of body-fin interactions for swimming, there are few data indicating whether body and fin configurations evolve in concert, or whether these structures vary independently. The cichlid fishes are a diverse family whose well-studied phylogenetic relationships make them ideal for the study of macroevolution of ecomorphology. This study measured body, and caudal and median fin morphology from radiographs of 131 cichlid genera, using morphometrics and phylogenetic comparative methods to determine whether these traits exhibit correlated evolution. Partial least squares canonical analysis revealed that body, caudal fin, dorsal fin, and anal fin shapes all exhibited strong correlated evolution consistent with locomotor ecomorphology. Major patterns included the evolution of deep body profiles with long fins, suggestive of maneuvering specialization; and the evolution of narrow, elongate caudal peduncles with concave tails, a combination that characterizes economical cruisers. These results demonstrate that body shape evolution does not occur independently of other traits, but among a suite of other morphological changes that augment locomotor specialization. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

A survey of radiation safety training among South African interventionalists

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A Rose

2018-04-01

Full Text Available Background. Ionising radiation is increasingly being used in modern medicine for diagnostic, interventional and therapeutic purposes. There has been an improvement in technology, resulting in lower doses being emitted. However, an increase in the number of procedures has led to a greater cumulative dose for patients and operators, which places them at increased risk of the effects of ionising radiation. Radiation safety training is key to optimising medical practice.Objective. To present the perceptions of South African interventionalists on the radiation safety training they received and to offer insights into the importance of developing and promoting such training programmes for all interventionalists.Methods. In this cross-sectional study, we collected data from interventionalists (N=108 using a structured questionnaire.Results. All groups indicated that radiation exposure in the workplace is important (97.2%. Of the participants, the radiologists received the most training (65.7%. Some participants (44.1% thought that their radiation safety training was adequate. Most participants (95.4% indicated that radiation safety should be part of their training curriculum. Few (34.3% had received instruction on radiation safety when they commenced work. Only 62% had been trained on how to protect patients from ionising radiation exposure.Conclusion. Radiation safety training should be formalised in the curriculum of interventionalists’ training programmes, as this will assist in stimulating a culture of radiation protection, which in turn will improve patient safety and improve quality of care.

Tiny worms from a mighty continent: high diversity and new phylogenetic lineages of African monogeneans.

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Přikrylová, Iva; Vanhove, Maarten P M; Janssens, Steven B; Billeter, Paul A; Huyse, Tine

2013-04-01

The family Gyrodactylidae contains one of the most significant radiations of platyhelminth fish parasites. The so-called hyperviviparity is very rare in the animal kingdom, and the rapid generation time can lead to an explosive population growth, which can cause massive losses in farmed fish. Here we present the first molecular phylogeny including all-but-one African genera, inferred from ITS and 18S rDNA sequences. The validity of nominal genera is discussed in relation to the systematic value of morphological characters traditionally used for generic identification. New complete 18S rDNA sequences of 18 gyrodactylid species of eight genera together with ITS rDNA gene sequences of eight species representing seven genera were generated and complemented with GenBank sequences. The maximum likelihood and Bayesian analyses pointed to a paraphyletic nature of African Gyrodactylus species. They formed well-supported clades possibly indicating speciation within host taxa: (1) parasites of cichlids (Cichlidae); (2) parasites of catfishes (Siluriformes), consisting of a lineage infecting mochokids and one infecting clariids. Macrogyrodactylus spp. firmly clustered into a monophyletic group. We found that Swingleus and Fundulotrema are very closely related and clearly cluster within Gyrodactylus. This supports earlier claims as to the paraphyly of the nominal genus Gyrodactylus as it is currently defined, and necessitates a revision of Swingleus and Fundulotrema. Molecular dating estimates confirmed a relatively young, certainly post-Gondwanan, origin of gyrodactylid lineages. Building on the previously suggested South-American origin of viviparous gyrodactylids, the dataset suggests subsequent intercontinental dispersal to Africa and from there repeated colonisation of the Holarctic. Even though the African continent has been heavily under sampled, the present diversity is far greater than in the intensively studied European fauna, probably because of the high endemicity

Aerosol optical, microphysical and radiative forcing properties during variable intensity African dust events in the Iberian Peninsula

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Fernández, A. J.; Molero, F.; Salvador, P.; Revuelta, A.; Becerril-Valle, M.; Gómez-Moreno, F. J.; Artíñano, B.; Pujadas, M.

2017-11-01

Aerosol measurements at two AERONET (AErosol RObotic NETwork) sites of the Iberian Peninsula: Madrid (40°.45N, 3.72W) and La Coruña (43°.36N, 8°.42W) have been analyzed for the period 2012-2015 to assess aerosol optical properties (intensive and extensive) throughout the atmospheric column and their radiative forcing (RF) and radiative forcing efficiency (RFeff) estimates at the Bottom and Top Of Atmosphere (BOA and TOA respectively). Specific conditions as dust-free and African dust have been considered for the study. Unprecedented, this work uses the quantification of the African dust aerosol at ground level which allows us to study such AERONET products at different intensity levels of African events: Low (L), High (H) and very high (VH). The statistical difference between dust-free and African dust conditions on the aforementioned parameters, quantified by means of the non-parametric Kolmogorov-Smirnov test, is quite clear in Madrid, however it is not in La Coruña. Scattering Angstrom Exponent (SAE) and Absorption Angstrom Exponent (AAE) were found to be 1.64 ± 0.29 and 1.14 ± 0.23 respectively in Madrid for dust-free conditions because typical aerosol sources are traffic emissions and residential heating, and black carbon is an important compound in this aerosol kind. On the other hand, SAE and AAE were 0.96 ± 0.60 and 1.44 ± 0.51 for African dust conditions in this location. RF (at shortwave radiation) seems to decrease as the African dust contribution at ground level is larger which indicates the cooling effect of African dust aerosol in Madrid. We have also proved the potential of a 2D-cluster analysis based on AAE and SAE to differentiate both situations in Madrid. Conversely, it is suggested that aerosols observed in La Coruña under dust-free conditions might come from different sources. Then, SAE and AAE are not good enough indicators to distinguish between dust-free and African dust conditions. Besides, as La Coruña is at a further distance

Developmental finite element analysis of cichlid pharyngeal jaws: Quantifying the generation of a key innovation

Science.gov (United States)

Müller, Gerd B.

2018-01-01

Advances in imaging and modeling facilitate the calculation of biomechanical forces in biological specimens. These factors play a significant role during ontogenetic development of cichlid pharyngeal jaws, a key innovation responsible for one of the most prolific species diversifications in recent times. MicroCT imaging of radiopaque-stained vertebrate embryos were used to accurately capture the spatial relationships of the pharyngeal jaw apparatus in two cichlid species (Haplochromis elegans and Amatitlania nigrofasciata) for the purpose of creating a time series of developmental stages using finite element models, which can be used to assess the effects of biomechanical forces present in a system at multiple points of its ontogeny. Changes in muscle vector orientations, bite forces, force on the neurocranium where cartilage originates, and stress on upper pharyngeal jaws are analyzed in a comparative context. In addition, microCT scanning revealed the presence of previously unreported cement glands in A. nigrofasciata. The data obtained provide an underrepresented dimension of information on physical forces present in developmental processes and assist in interpreting the role of developmental dynamics in evolution. PMID:29320528

Developmental finite element analysis of cichlid pharyngeal jaws: Quantifying the generation of a key innovation.

Directory of Open Access Journals (Sweden)

Tim Peterson

Full Text Available Advances in imaging and modeling facilitate the calculation of biomechanical forces in biological specimens. These factors play a significant role during ontogenetic development of cichlid pharyngeal jaws, a key innovation responsible for one of the most prolific species diversifications in recent times. MicroCT imaging of radiopaque-stained vertebrate embryos were used to accurately capture the spatial relationships of the pharyngeal jaw apparatus in two cichlid species (Haplochromis elegans and Amatitlania nigrofasciata for the purpose of creating a time series of developmental stages using finite element models, which can be used to assess the effects of biomechanical forces present in a system at multiple points of its ontogeny. Changes in muscle vector orientations, bite forces, force on the neurocranium where cartilage originates, and stress on upper pharyngeal jaws are analyzed in a comparative context. In addition, microCT scanning revealed the presence of previously unreported cement glands in A. nigrofasciata. The data obtained provide an underrepresented dimension of information on physical forces present in developmental processes and assist in interpreting the role of developmental dynamics in evolution.

Tenth national congress of the South African Society of Radiation Therapists

International Nuclear Information System (INIS)

1986-01-01

The proceedings of the tenth national congress of the South African Society of Radiation Therapists are presented. Papers on the following topics were presented: gynaecological malignancies and oncology; pain and symptom control; radiobiology; radiotherapy of the head and neck; combined modality therapy, and lymphoma. Separate abstracts were prepared for thirty five of the papers presented. The remaining papers were considered outside the subject scope of INIS

The role of rare morph advantage and conspicuousness in the stable gold-dark colour polymorphism of a crater lake Midas cichlid fish.

Science.gov (United States)

Torres-Dowdall, Julián; Golcher-Benavides, Jimena; Machado-Schiaffino, Gonzalo; Meyer, Axel

2017-09-01

Genetically based stable colour polymorphisms provide a unique opportunity to study the evolutionary processes that preserve genetic variability in the wild. Different mechanisms are proposed to promote the stability of polymorphisms, but only few empirical examples have been documented, resulting in an incomplete understanding of these mechanisms. A remarkable genetically determined stable colour polymorphism is found in the Nicaraguan Midas cichlid species complex (Amphilophus cf. citrinellus). All Midas cichlids start their life with a dark-grey coloration (dark morph), but individuals carrying the dominant "gold" allele (c. 10%) lose their melanophores later in life, revealing the underlying orange coloration (gold morph). How this polymorphism is maintained remains unclear. Two main hypotheses have been proposed, both suggesting differential predation upon colour morphs as the proximate mechanism. One predicts that the conspicuous gold morph is more likely to be preyed upon, but this disadvantage is balanced by their competitive dominance over the dark morph. The second hypothesis suggests a rare morph advantage where the rarer gold morph experiences less predation. Empirical evidence for either of these mechanisms is still circumstantial and inconclusive. We conducted two field experiments in a Nicaraguan crater lake using wax models simulating both morphs to determine predation pressure upon Midas cichlid colour morphs. First, we tested the interaction of coloration and depth on attack rate. Second, we tested the interaction of fish size and coloration. We contrasted the pattern of attacks from these experiments to the predicted predation patterns from the hypotheses proposed to explain the colour polymorphism's stability. Large models imitating colour morphs were attacked at similar rates irrespectively of their position in the water column. Yet, attacks upon small models resembling juveniles were directed mainly towards dark models. This resulted in a

Species-specific relationships between water transparency and male coloration within and between two closely related Lake Victoria cichlid species

NARCIS (Netherlands)

Castillo Cajas, Ruth F; Selz, Oliver M; Ripmeester, Erwin A P; Seehausen, Ole; Maan, Martine E

2012-01-01

Environmental variation in signalling conditions affects animal communication traits, with possible consequences for sexual selection and reproductive isolation. Using spectrophotometry, we studied how male coloration within and between populations of two closely related Lake Victoria cichlid

Male convict cichlid 11-ketotestosterone levels throughout the reproductive cycle: an exploratory profile study in laboratory and field populations

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Natalie April van Breukelen

2015-05-01

Full Text Available The convict cichlid (Amatitlania nigrofasciata has been extensively examined in relation to many behavioral topics, such as courtship, pair-bonding, bi-parental care, and territoriality. Recently, this model species has been utilized in studies on genetics, endocrinology, and neuroanatomy, with an ultimate goal of connecting behavior with its underlying mechanisms. The goal of this study was two-fold: (1 profile the circulating levels of plasma 11KT in the male convict cichlid at multiple points during the reproductive cycle and (2 generally compare the hormonal profiles of the widely used laboratory populations and those of a free-living population in the streams of Costa Rica. The results of the field experiment showed that male convict cichlids had higher levels of circulating 11KT during courtship and lower during the parental care and non-breeding phases. The profile of the laboratory population was similar to the profile of the free-living individuals, with significantly higher levels of 11KT occurring during courtship than during parental care, though the level of 11KT during non-breeding phase was elevated in the laboratory. The high levels of 11KT during courtship and low levels of 11KT during parental care found in both the field and the laboratory is similar to what has been reported in other species of teleosts, and may suggest an important function of 11KT in the expression of courtship behavior and the subsequent onset of parental behaviors in this model species.

Adaptive landscape and functional diversity of Neotropical cichlids: implications for the ecology and evolution of Cichlinae (Cichlidae; Cichliformes).

Science.gov (United States)

Arbour, J H; López-Fernández, H

2014-11-01

Morphological, lineage and ecological diversity can vary substantially even among closely related lineages. Factors that influence morphological diversification, especially in functionally relevant traits, can help to explain the modern distribution of disparity across phylogenies and communities. Multivariate axes of feeding functional morphology from 75 species of Neotropical cichlid and a stepwise-AIC algorithm were used to estimate the adaptive landscape of functional morphospace in Cichlinae. Adaptive landscape complexity and convergence, as well as the functional diversity of Cichlinae, were compared with expectations under null evolutionary models. Neotropical cichlid feeding function varied primarily between traits associated with ram feeding vs. suction feeding/biting and secondarily with oral jaw muscle size and pharyngeal crushing capacity. The number of changes in selective regimes and the amount of convergence between lineages was higher than expected under a null model of evolution, but convergence was not higher than expected under a similarly complex adaptive landscape. Functional disparity was compatible with an adaptive landscape model, whereas the distribution of evolutionary change through morphospace corresponded with a process of evolution towards a single adaptive peak. The continentally distributed Neotropical cichlids have evolved relatively rapidly towards a number of adaptive peaks in functional trait space. Selection in Cichlinae functional morphospace is more complex than expected under null evolutionary models. The complexity of selective constraints in feeding morphology has likely been a significant contributor to the diversity of feeding ecology in this clade. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

A COMPARATIVE-STUDY OF STIMULUS SELECTION IN THE FILIAL FOLLOWING RESPONSE OF FRY OF SUBSTRATE SPAWNING CICHLID FISH

NARCIS (Netherlands)

BAERENDS, GP

This paper reports on experimental research undertaken to analyse the information processing mechanism by which the fry of substrate spawning cichlid fish visually recognise their guarding parent(s), already from the earliest time they are able to swim. The study is inspired by LORENZ' concept of

Age, growth, and mortality of the Mayan cichlid (Cichlasoma urophthalmus) from the southeastern Everglades

OpenAIRE

Faunce, Craig H.; Patterson, Heather M.; Lorenz, Jerome J.

2002-01-01

Mayan cichlids (Cichlasoma urophthalmus) were collected monthly from March 1996 to October 1997 with hook-and-line gear at Taylor River, Florida, an area within the Crocodile Sanctuary of Everglades National Park, where human activities such as fishing are prohibited. Fish were aged by examining thin-sectioned otoliths, and past size-at-age information was generated by using back-calculation techniques. Marginal increment analysis showed that opaque growth zones were annuli deposited between ...

Hedgehog signaling mediates adaptive variation in a dynamic functional system in the cichlid feeding apparatus.

Science.gov (United States)

Hu, Yinan; Albertson, R Craig

2014-06-10

Adaptive variation in the craniofacial skeleton is a key component of resource specialization and habitat divergence in vertebrates, but the proximate genetic mechanisms that underlie complex patterns of craniofacial variation are largely unknown. Here we demonstrate that the Hedgehog (Hh) signaling pathway mediates widespread variation across a complex functional system that affects the kinematics of lower jaw depression--the opercular four-bar linkage apparatus--among Lake Malawi cichlids. By using a combined quantitative trait locus mapping and population genetics approach, we show that allelic variation in the Hh receptor, ptch1, affects the development of distinct bony elements in the head that represent two of three movable links in this functional system. The evolutionarily derived allele is found in species that feed from the water column, and is associated with shifts in anatomy that translate to a four-bar system capable of faster jaw rotation. Alternatively, the ancestral allele is found in species that feed on attached algae, and is associated with the development of a four-bar system that predicts slower jaw movement. Experimental manipulation of the Hh pathway during cichlid development recapitulates functionally salient natural variation in craniofacial geometry. In all, these results significantly extend our understanding of the mechanisms that fine-tune the craniofacial skeletal complex during adaptation to new foraging niches.

Discordant genetic diversity and geographic patterns between Crassicutis cichlasomae (Digenea: Apocreadiidae) and its cichlid host, "Cichlasoma" urophthalmus (Osteichthyes: Cichlidae), in Middle-America.

Science.gov (United States)

Razo-Mendivil, Ulises; Vázquez-Domínguez, Ella; de León, Gerardo Pérez-Ponce

2013-12-01

Genetic analyses of hosts and their parasites are key to understand the evolutionary patterns and processes that have shaped host-parasite associations. We evaluated the genetic structure of the digenean Crassicutis cichlasomae and its most common host, the Mayan cichlid "Cichlasoma" urophthalmus, encompassing most of their geographical range in Middle-America (river basins in southeastern Mexico, Belize, and Guatemala together with the Yucatan Peninsula). Genetic diversity and structure analyses were done based on 167 cytochrome c oxidase subunit 1 sequences (330 bp) for C. cichlasomae from 21 populations and 161 cytochrome b sequences (599 bp) for "C." urophthalmus from 26 populations. Analyses performed included phylogenetic tree estimation under Bayesian inference and maximum likelihood analysis, genetic diversity, distance and structure estimates, haplotype networks, and demographic evaluations. Crassicutis cichlasomae showed high genetic diversity values and genetic structuring, corresponding with 4 groups clearly differentiated and highly divergent. Conversely, "C." urophthalmus showed low levels of genetic diversity and genetic differentiation, defined as 2 groups with low divergence and with no correspondence with geographical distribution. Our results show that species of cichlids parasitized by C. cichlasomae other than "C." urophthalmus, along with multiple colonization events and subsequent isolation in different basins, are likely factors that shaped the genetic structure of the parasite. Meanwhile, historical long-distance dispersal and drought periods during the Holocene, with significant population size reductions and fragmentations, are factors that could have shaped the genetic structure of the Mayan cichlid.

Community genetics reveal elevated levels of sympatric gene flow among morphologically similar but not among morphologically dissimilar species of Lake Victoria cichlid fish

NARCIS (Netherlands)

Konijnendijk, N.; Joyce, D.A.; Mrosso, H.D.J.; Egas, M.; Seehausen, O.

2011-01-01

We examined genetic structure among five species of Lake Victoria haplochromine cichlids in four island communities, using a full factorial sampling design that compared genetic differentiation between pairs of species and populations of varying morphological similarity and geographical proximity.

Gonad development in Midas cichlids and the evolution of sex change in fishes.

Science.gov (United States)

Oldfield, Ronald G

2011-01-01

Some fishes mature and function as one sex and later transform to the other sex in response to social interactions. Previous evidence suggested that a change in developmental timing may be involved in the evolution of adult sex change in fishes. The most recent support for this idea came from reports that sex in the Midas cichlid, Amphilophus citrinellus, was determined by social conditions experienced at the juvenile stage. Differentiation as a male was reported to be dependent on large body size relative to group-mates, and thought to be mediated through aggressive interactions. Here I demonstrate that socially controlled sex determination does not occur as was originally reported. Previously, I found that sex was not associated with body size in juveniles either in nature or in captivity. Similarly, I found no association between aggressive behavior and sex in juveniles. I later demonstrated that socially controlled sex determination does not typically occur in the Midas cichlid and closely related species and supported an alternative mechanism to explain large body size in adult males. Finally, in the current study I analyze gonad histology of fish from the same population used by the original authors and lay to rest the idea of socially controlled sex determination in this species. Recent observations of socially controlled sex determination in juveniles of species that typically change sex at the adult stage are examples of phenotypic plasticity, not genetic variation. Therefore, juvenile socially controlled sex determination does not support a theory that a change in developmental timing is involved in the evolution of adult sex change in fishes. © 2011 Wiley Periodicals, Inc.

Assessment of Mercury Bioaccumulation in Zebra Cichlid (Cichlasoma Nigrofasciatum Exposed to Sublethal Concentrations of Permethrin

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Mahdi Banaee

2014-12-01

Full Text Available Background: Aquatic ecosystems are frequently subjected to contamination by toxic heavy metals and pesticides, yet very little is known about the influence of pesticides on bioaccumulation of heavy metals in aquatic organisms. Mercury is a toxic metal with no known biological benefit to organisms. Bioavailability of mercury in aquatic environments depends on biological and non-biological parameters including other pollutants. Therefore, the objectives of this research were to determine the effects of permethrin on bioaccumulation of mercury in zebra cichlid. Methods: Acute toxicity (LC50 of permethrin and mercury chloride was evaluated by estimating mortality in Probit Model in SPSS (version 19.0 IBM. In sub-lethal toxicity, zebra cichlid (Cichlasoma nigrofasciatum was exposed to various concentrations of permethrin (0.0, 0.40, 0.80, 1.20 and 1.60 µg.L-1 combined with 20 µg.L-1 mercury chloride for 15 days. At the end of the experiment, mercury concentrations were measured using ICP-OES-Perkin elmer (optima 7300-DV. Results: 96 h LC50 values of permethrin and mercury for C. nigrofasciatum were calculated to be 17.55 µg.L-1 and 140.38 µg.L-1, respectively. Our results clearly showed that the bioaccumulation of mercury in the specimens increased with increasing concentrations of permethrin to 1.20 and 1.60 µg.L-1. Conclusion: Increasing the concentration of permethrin had synergistic effects on the bioaccumulation of mercury in fish.

A new cryptogonimid (Digenea) from the Mayan cichlid, Cichlasoma urophthalmus (Osteichthyes: Cichlidae), in several localities of the Yucatán Peninsula, Mexico.

Science.gov (United States)

Razo-Mendivil, Ulises; Rosas-Valdez, Rogelio; Pérez-Ponce de León, Gerardo

2008-12-01

Oligogonotylus mayae n.sp. is described from the intestine of the Mayan cichlid Cichlasoma urophthalmus (Günther) in Ría Lagartos, Ría Celestún, and Estero Progreso, Yucatán State. This is the second species described for Oligogonotylus Watson, 1976, the other being O.manteri Watson, 1976. The new species is readily distinguished from O. manteri by the anterior extension of the vitelline follicles. In O. Manteri, Vitelline follicles are found entirely in the hindbody, extending posteriorly to mid-testicular level. Vitelline follicles in the new species extend from teh anterior margin of posterior testis to the region between the bentral sucker and the pharynx. comparison of approximately 1,850 bases of ribosomal DNA (ITS1, ITS2, 5.8S, and 28S), and 400 bases of cytochrome c oxidase subunit I (cox1) strongly supports the status of O. mayae as a new species, as compared to O. manteri collected from cichlids in other localities of Mexico, Belize, and Guatemala.

Parental investment matters for maternal and offspring immune defense in the mouthbrooding cichlid Astatotilapia burtoni.

Science.gov (United States)

Keller, Isabel S; Salzburger, Walter; Roth, Olivia

2017-12-20

Parental care, while increasing parental fitness through offspring survival, also bears cost to the care-giving parent. Consequentially, trade offs between parental care and other vitally important traits, such as the immune system seem evident. In co-occurring phases of parental care and immunological challenges negative consequences through a resource allocation trade off on both the parental and the offspring conditions can be predicted. While the immune system reflects parental stress conditions, parental immunological investments also boost offspring survival via the transfer of immunological substances (trans-generational immune priming). We investigated this relationship in the mouthbrooding East African cichlid Astotatilapia burtoni. Prior to mating, females were exposed to an immunological activation, while others remained immunologically naïve. Correspondingly, the immunological status of females was either examined directly after reproduction or after mouthbrooding had ceased. Offspring from both groups were exposed to immunological challenges to assess the extent of trans-generational immune priming. As proxy for immune status, cellular immunological activity and gene expression were determined. Both reproducing and mouthbrooding females allocate their resources towards reproduction. While upon reproduction the innate immune system was impeded, mouthbrooding females showed an attenuation of inflammatory components. Juveniles from immune challenged mouthbrooding females showed downregulation of immune and life history candidate genes, implying a limitation of trans-generational plasticity when parents experience stress during the costly reproductive phase. Our results provide evidence that both parental investment via mouthbrooding and the rise of the immunological activity upon an immune challenge are costly traits. If applied simultaneously, not only mothers seem to be impacted in their performance, but also offspring are impeded in their ability to

Lateralized behaviour of a non-social cichlid fish (Amatitlania nigrofasciata) in a social and a non-social environment.

Science.gov (United States)

Moscicki, Michele K; Reddon, Adam R; Hurd, Peter L

2011-09-01

Cerebral lateralization, the partitioning of cognitive function preferentially into one hemisphere of the brain, is a trait ubiquitous among vertebrates. Some species exhibit population level lateralization, where the pattern of cerebral lateralization is the same for most members of that species; however, other species show only individual level lateralization, where each member of the species has a unique pattern of lateralized brain function. The pattern of cerebral lateralization within a population and an individual has been shown to differ based on the stimulus being processed. It has been hypothesized that sociality within a species, such as shoaling behaviour in fish, may have led to the development and persistence of population level lateralization. Here we assessed cerebral lateralization in convict cichlids (Amatitlania nigrofasciata), a species that does not shoal as adults but that shoals briefly as juveniles. We show that both male and female convict cichlids display population level lateralization when in a solitary environment but only females show population level lateralization when in a perceived social environment. We also show that the pattern of lateralization differs between these two tasks and that strength of lateralization in one task is not predictive of strength of lateralization in the other task. Copyright © 2011 Elsevier B.V. All rights reserved.

Induced cytochrome P450 1A activity in cichlid fishes from Guandu River and Jacarepagua Lake, Rio de Janeiro, Brazil

International Nuclear Information System (INIS)

Parente, Thiago E.M.; Oliveira, Ana C.A.X. de; Paumgartten, Francisco J.R.

2008-01-01

The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ('Nile tilapia', Oreochromis niloticus and 'acara', Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepagua Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes. - Increased EROD activity in the liver of cichlid fishes indicated that Guandu River, the source of drinking water supply for Rio de Janeiro is polluted by CYP1A-inducing chemicals

Genetic, comparative genomic, and expression analyses of the Mc1r locus in the polychromatic Midas cichlid fish (Teleostei, Cichlidae Amphilophus sp.) species group.

Science.gov (United States)

Henning, Frederico; Renz, Adina Josepha; Fukamachi, Shoji; Meyer, Axel

2010-05-01

Natural populations of the Midas cichlid species in several different crater lakes in Nicaragua exhibit a conspicuous color polymorphism. Most individuals are dark and the remaining have a gold coloration. The color morphs mate assortatively and sympatric population differentiation has been shown based on neutral molecular data. We investigated the color polymorphism using segregation analysis and a candidate gene approach. The segregation patterns observed in a mapping cross between a gold and a dark individual were consistent with a single dominant gene as a cause of the gold phenotype. This suggests that a simple genetic architecture underlies some of the speciation events in the Midas cichlids. We compared the expression levels of several candidate color genes Mc1r, Ednrb1, Slc45a2, and Tfap1a between the color morphs. Mc1r was found to be up regulated in the gold morph. Given its widespread association in color evolution and role on melanin synthesis, the Mc1r locus was further investigated using sequences derived from a genomic library. Comparative analysis revealed conserved synteny in relation to the majority of teleosts and highlighted several previously unidentified conserved non-coding elements (CNEs) in the upstream and downstream regions in the vicinity of Mc1r. The identification of the CNEs regions allowed the comparison of sequences from gold and dark specimens of natural populations. No polymorphisms were found between in the population sample and Mc1r showed no linkage to the gold phenotype in the mapping cross, demonstrating that it is not causally related to the color polymorphism in the Midas cichlid.

Induced cytochrome P450 1A activity in cichlid fishes from Guandu River and Jacarepagua Lake, Rio de Janeiro, Brazil

Energy Technology Data Exchange (ETDEWEB)

Parente, Thiago E.M.; Oliveira, Ana C.A.X. de [Laboratorio de Toxicologia Ambiental, Escola Nacional de Saude Publica - FIOCRUZ, Av Brasil 4036, Predio de Expansao do Campus, Rio de Janeiro, RJ 21041-361 (Brazil); Paumgartten, Francisco J.R. [Laboratorio de Toxicologia Ambiental, Escola Nacional de Saude Publica - FIOCRUZ, Av Brasil 4036, Predio de Expansao do Campus, Rio de Janeiro, RJ 21041-361 (Brazil)], E-mail: paum@ensp.fiocruz.br

2008-03-15

The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ('Nile tilapia', Oreochromis niloticus and 'acara', Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepagua Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes. - Increased EROD activity in the liver of cichlid fishes indicated that Guandu River, the source of drinking water supply for Rio de Janeiro is polluted by CYP1A-inducing chemicals.

African Zoology - Vol 35, No 2 (2000)

African Journals Online (AJOL)

The reproductive biology of an open-water spawning Lake Malawi cichlid, Copadichromis chrysonotus · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Lance W. Smith, 151-164. http://dx.doi.org/10.1080/15627020.2000.11657086 ...

Interspecific competition, predation, and the coexistence of three closely related neotropical armoured catfishes (Siluriformes - Callichthyidae)

NARCIS (Netherlands)

Mol, J.H.A.

1995-01-01

Tropical ecosystems are renowned for their high biodiversity with many closely related species living together. Alpha diversity of tropical freshwater fishes is also extremely high, as exemplified by the cichlid fauna of the Great African lakes and the neotropical characins. Since

Impact of increased ultraviolet-B radiation stress due to stratospheric ozone depletion on N2 fixation in traditional African commercial legumes

International Nuclear Information System (INIS)

Chimphango, S.B.M.; Musil, C.F.; Dakora, F.D.

2004-01-01

Reports of diminished nodule formation and nitroge-nase activity in some Asian tropical legumes exposed to above-ambient levels of ultraviolet-B (UV-B: 280-315nm) radiation have raised concerns as to the impact of stratospheric ozone depletion on generally poorly developed traditional African farming systems confronted by the high cost and limited availability of chemical fertilisers. These rely on N 2 -fixing legumes as the cheapest source of N for maintaining soil fertility and sustainable yields in the intrinsically infertile and heterogeneous African soils. In view of this, we examined the effects of supplemental UV-B radiation approximating 15% and 25% depletions in the total ozone column on N 2 fixation in eight traditional African commercial legume species representing crop, forest, medicinal, ornamental and pasture categories. In all categories examined, except medicinal, supplemental UV-B had no effect on root non-structural carbohydrates, antho-cyanins and flavonoids, known to signal Rhizobiaceae micro-symbionts and promote nodule formation, or on nodule mass, activity and quantities of N fixed in different plant organs and whole plants. In contrast, in the medicinal category Cyclopia maculata (Honeybush) a slow growing commercially important herbal beverage with naturally high flavonoid concentrations, displayed decreased nodule activity and quantities of N fixed in different plant organs and whole plants with increased UV-B. This study's findings conclude negligible impacts of ozone depletion on nitrogen fixation and soil fertility in most traditional African farming systems, these limited to occasional inhibition of nodule induction in some crops. (author)

Paternity of subordinates raises cooperative effort in cichlids.

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Rick Bruintjes

Full Text Available In cooperative breeders, subordinates generally help a dominant breeding pair to raise offspring. Parentage studies have shown that in several species subordinates can participate in reproduction. This suggests an important role of direct fitness benefits for cooperation, particularly where groups contain unrelated subordinates. In this situation parentage should influence levels of cooperation. Here we combine parentage analyses and detailed behavioural observations in the field to study whether in the highly social cichlid Neolamprologus pulcher subordinates participate in reproduction and if so, whether and how this affects their cooperative care, controlling for the effect of kinship.We show that: (i male subordinates gained paternity in 27.8% of all clutches and (ii if they participated in reproduction, they sired on average 11.8% of young. Subordinate males sharing in reproduction showed more defence against experimentally presented egg predators compared to subordinates not participating in reproduction, and they tended to stay closer to the breeding shelter. No effects of relatedness between subordinates and dominants (to mid-parent, dominant female or dominant male were detected on parentage and on helping behaviour.This is the first evidence in a cooperatively breeding fish species that the helping effort of male subordinates may depend on obtained paternity, which stresses the need to consider direct fitness benefits in evolutionary studies of helping behaviour.

Water-level fluctuations and metapopulation dynamics as drivers of genetic diversity in populations of three Tanganyikan cichlid fish species.

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Nevado, B; Mautner, S; Sturmbauer, C; Verheyen, E

2013-08-01

Understanding how genetic variation is generated and maintained in natural populations, and how this process unfolds in a changing environment, remains a central issue in biological research. In this work, we analysed patterns of genetic diversity from several populations of three cichlid species from Lake Tanganyika in parallel, using the mitochondrial DNA control region. We sampled populations inhabiting the littoral rocky habitats in both very deep and very shallow areas of the lake. We hypothesized that the former would constitute relatively older, more stable and genetically more diverse populations, because they should have been less severely affected by the well-documented episodes of dramatic water-level fluctuations. In agreement with our predictions, populations of all three species sampled in very shallow shorelines showed traces of stronger population growth than populations of the same species inhabiting deep shorelines. However, contrary to our working hypothesis, we found a significant trend towards increased genetic diversity in the younger, demographically less stable populations inhabiting shallow areas, in comparison with the older and more stable populations inhabiting the deep shorelines. We interpret this finding as the result of the establishment of metapopulation dynamics in the former shorelines, by the frequent perturbation and reshuffling of individuals between populations due to the lake-level fluctuations. The repeated succession of periods of allopatric separation and secondary contact is likely to have further increased the rapid pace of speciation in lacustrine cichlids. © 2013 John Wiley & Sons Ltd.

The pervasive crisis of diminishing radiation therapy access for vulnerable populations in the United States, part 1: African-American patients.

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McClelland, Shearwood; Page, Brandi R; Jaboin, Jerry J; Chapman, Christina H; Deville, Curtiland; Thomas, Charles R

2017-01-01

African Americans experience the highest burden of cancer incidence and mortality in the United States and have been persistently less likely to receive interventional care, even when such care has been proven superior to conservative management by randomized controlled trials. The presence of disparities in access to radiation therapy (RT) for African American cancer patients has rarely been examined in an expansive fashion. An extensive literature search was performed using the PubMed database to examine studies investigating disparities in RT access for African Americans. A total of 55 studies were found, spanning 11 organ systems. Disparities in access to RT for African Americans were most prominently study in cancers of the breast (23 studies), prostate (7 studies), gynecologic system (5 studies), and hematologic system (5 studies). Disparities in RT access for African Americans were prevalent regardless of organ system studied and often occurred independently of socioeconomic status. Fifty of 55 studies (91%) involved analysis of a population-based database such as Surveillance, Epidemiology and End Result (SEER; 26 studies), SEER-Medicare (5 studies), National Cancer Database (3 studies), or a state tumor registry (13 studies). African Americans in the United States have diminished access to RT compared with Caucasian patients, independent of but often in concert with low socioeconomic status. These findings underscore the importance of finding systemic and systematic solutions to address these inequalities to reduce the barriers that patient race provides in receipt of optimal cancer care.

Changes in the acoustic environment alter the foraging and sheltering behaviour of the cichlid Amititlania nigrofasciata.

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McLaughlin, Kirsty Elizabeth; Kunc, Hansjoerg P

2015-07-01

Anthropogenic noise can affect behaviour across a wide range of species in both terrestrial and aquatic environments. However, behaviours might not be affected in isolation. Therefore, a more holistic approach investigating how environmental stressors, such as noise pollution, affect different behaviours in concert is necessary. Using tank-based noise exposure experiments, we tested how changes in the acoustic environment affect the behaviour of the cichlid Amatitlania nigrofasciata. We found that exposure to anthropogenic noise affected a couple of behaviours: an increase in sheltering was accompanied by a decrease in foraging. Our results highlight the multiple negative effects of an environmental stressor on an individual's behaviour. Copyright © 2015 Elsevier B.V. All rights reserved.

The Impact of Desert Dust Aerosol Radiative Forcing on Global and West African Precipitation

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Jordan, A.; Zaitchik, B. F.; Gnanadesikan, A.; Dezfuli, A. K.

2015-12-01

Desert dust aerosols exert a radiative forcing on the atmosphere, influencing atmospheric temperature structure and modifying radiative fluxes at the top of the atmosphere (TOA) and surface. As dust aerosols perturb radiative fluxes, the atmosphere responds by altering both energy and moisture dynamics, with potentially significant impacts on regional and global precipitation. Global Climate Model (GCM) experiments designed to characterize these processes have yielded a wide range of results, owing to both the complex nature of the system and diverse differences across models. Most model results show a general decrease in global precipitation, but regional results vary. Here, we compare simulations from GFDL's CM2Mc GCM with multiple other model experiments from the literature in order to investigate mechanisms of radiative impact and reasons for GCM differences on a global and regional scale. We focus on West Africa, a region of high interannual rainfall variability that is a source of dust and that neighbors major Sahara Desert dust sources. As such, changes in West African climate due to radiative forcing of desert dust aerosol have serious implications for desertification feedbacks. Our CM2Mc results show net cooling of the planet at TOA and surface, net warming of the atmosphere, and significant increases in precipitation over West Africa during the summer rainy season. These results differ from some previous GCM studies, prompting comparative analysis of desert dust parameters across models. This presentation will offer quantitative analysis of differences in dust aerosol parameters, aerosol optical properties, and overall particle burden across GCMs, and will characterize the contribution of model differences to the uncertainty of forcing and climate response affecting West Africa.

Environment, Health and Climate: Impact of African aerosols

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Liousse, C.; Doumbia, T.; Assamoi, E.; Galy-Lacaux, C.; Baeza, A.; Penner, J. E.; Val, S.; Cachier, H.; Xu, L.; Criqui, P.

2012-12-01

Fossil fuel and biofuel emissions of particles in Africa are expected to significantly increase in the near future, particularly due to rapid growth of African cities. In addition to biomass burning emissions prevailing in these areas, air quality degradation is then expected with important consequences on population health and climatic/radiative impact. In our group, we are constructing a new integrated methodology to study the relations between emissions, air quality and their impacts. This approach includes: (1) African combustion emission characterizations; (2) joint experimental determination of aerosol chemistry from ultrafine to coarse fractions and health issues (toxicology and epidemiology). (3) integrated environmental, health and radiative modeling. In this work, we show some results illustrating our first estimates of African anthropogenic emission impacts: - a new African anthropogenic emission inventory adapted to regional specificities on traffic, biofuel and industrial emissions has been constructed for the years 2005 and 2030. Biomass burning inventories were also improved in the frame of AMMA (African Monsoon) program. - carbonaceous aerosol radiative impact in Africa has been modeled with TM5 model and Penner et al. (2011) radiative code for these inventories for 2005 and 2030 and for two scenarios of emissions : a reference scenario, with no further emission controls beyond those achieved in 2003 and a ccc* scenario including planned policies in Kyoto protocol and regulations as applied to African emission specificities. In this study we will show that enhanced heating is expected with the ccc* scenarios emissions in which the OC fraction is relatively lower than in the reference scenario. - results of short term POLCA intensive campaigns in Bamako and Dakar in terms of aerosol chemical characterization linked to specific emissions sources and their inflammatory impacts on the respiratory tract through in vitro studies. In this study, organic

Distribution and female reproductive state differences in orexigenic and anorexigenic neurons in the brain of the mouth brooding African cichlid fish, Astatotilapia burtoni.

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Porter, Danielle T; Roberts, David A; Maruska, Karen P

2017-10-01

Integration of reproduction and metabolism is necessary for species survival. While the neural circuits controlling energy homeostasis are well-characterized, the signals controlling the relay of nutritional information to the reproductive axis are less understood. The cichlid fish Astatotilapia burtoni is ideal for studying the neural regulation of feeding and reproduction because females cycle between a feeding gravid state and a period of forced starvation while they brood developing young inside their mouths. To test the hypothesis that candidate neuropeptide-containing neurons known to be involved in feeding and energy homeostasis in mammals show conserved distribution patterns, we performed immunohistochemistry and in situ hybridization to localize appetite-stimulating (neuropeptide Y, NPY; agouti-related protein, AGRP) and appetite-inhibiting (cocaine and amphetamine-regulated transcript, CART; pro-opiomelanocortin, pomc1a) neurons in the brain. NPY, AGRP, CART, and pomc1a somata showed distribution patterns similar to other teleosts, which included localization to the lateral tuberal nucleus (NLT), the putative homolog of the mammalian arcuate nucleus. Gravid females also had larger NPY and AGRP neurons in the NLT compared to brooding females, but brooding females had larger pomc1a neurons compared to gravid females. Hypothalamic agrp mRNA levels were also higher in gravid compared to brooding females. Thus, larger appetite-stimulating neurons (NPY, AGRP) likely promote feeding while females are gravid, while larger pomc1a neurons may act as a signal to inhibit food intake during mouth brooding. Collectively, our data suggest a potential role for NPY, AGRP, POMC, and CART in regulating energetic status in A. burtoni females during varying metabolic and reproductive demands. © 2017 Wiley Periodicals, Inc.

Diet and food consumption of the pearl cichlid Geophagus brasiliensis (Teleostei: Cichlidae: relationships with gender and sexual maturity

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Rodrigo F. Bastos

Full Text Available Despite the importance of the pearl cichlid Geophagus brasiliensis for the aquarium fish trade worldwide and its wide distribution, many aspects of its biology, such as the relationships between its feeding ecology and reproductive behavior, are not fully understood in natural conditions on its native habitat. In this paper, we investigated its diet focusing on how differences in diet and food consumption are related to differences in gender and sexual maturity. The digestive tract of each individual was dissected and had its content analyzed, whereas each gonad was microscopically analyzed to determine gender (male/female and sexual maturity (immature/mature. A total of 28 females and 31 males were analyzed. Mature individuals were more common than immature specimens both for males (64.50% and females (64.30%. The analysis of 52 individuals with non-empty digestive tracts revealed a diet comprised of 27 items. According to the Index of Alimentary importance (%IAi, the most important food items in the diet were Gastropoda (37.30%, fragments of vascular plants (15.16%, detritus (10.14%, Amphipoda (9.24%, and fish scales (6.29%. Mature males had more empty stomachs (65.00% when compared to immature males (27.27% and immature (55.56% and mature females (40.00%. Also, mature females seemed to have more food consumption (greater mean values of total volume in their digestive tracts than mature males. Some hypotheses are proposed in order to distinguish if this gender-based difference in food consumption in mature individuals of the pearl cichlid could be associated with the development of primary and secondary sexual characteristics or with asymmetrical time invested in parental care activities.

Dietary habits of juveniles of the Mayan cichlid, Cichlasoma urophthalmus, in mangrove ponds of an offshore islet in Belize, Central America

OpenAIRE

Vaslet, Amandine; France, Christine; Baldwin, Carole C.; Feller, Ilka C.

2012-01-01

Foraging habitats of juveniles of the Mayan cichlid, Cichlasoma urophthalmus (Günther, 1862), were investigated in two mangrove ponds located in Twin Cays offshore islet in Belize: Sink Hole pond (SH) and Hidden Lake pond (HL). Sink Hole pond is a semiclosed body of water, whereas Hidden Lake pond is connected by a channel to adjacent seagrass beds that surround the islet. Gut contents of 21 juvenile C. urophthalmus (9.8-13.2 cm total length) were analyzed, and five prey taxa were identified....

The first joint congress of the South African Biochemical Society, South African Genetics Society and the South African Society for Microbiology at the University of the Witwatersrand, 29 June-4 July 1986

International Nuclear Information System (INIS)

1986-01-01

The South African Biochemical Society, South African Genetics Society and the South African Society for Microbiology held a joint congress at the University of the Witwatersrand from 29 June - 4 July 1986. The papers delivered cover subjects such as Molecular biology, Genetics, Biochemistry, Medical biochemistry, Physiology, Zoology and Isotope and radiation sciences. Different isotopes are used in labelling studies of enzymes, nutrition, metabolism, viruses, bacteria and other biological assays done in the fields of Biochenmistry, Genetics and Microbiology. This work contains only the abstracts of these papers

Enigmatic tissue in the orobranchial chamber of cardinalfishes of the ...

African Journals Online (AJOL)

An unusual tissue covering the tongue and occasionally part of the gill chamber of many species of the Indo-Pacific cardinalfish genus Siphamia is described and compared with an earlier description of a similar tissue found in the cichlid species Alcolapia grahami inhabiting lakes of the African Rift Valley. Species of both ...

Direct Radiative Effect of Mineral Dust on the Development of African Easterly Wave in Late Summer, 2003-2007

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Ma, Po-Lun; Zhang, Kai; Shi, Jainn Jong; Matsui, Toshihisa; Arking, Albert

2012-01-01

Episodic events of both Saharan dust outbreaks and African Easterly Waves (AEWs) are observed to move westward over the eastern tropical Atlantic Ocean. The relationship between the warm, dry, and dusty Saharan Air Layer (SAL) on the nearby storms has been the subject of considerable debate. In this study, the Weather Research and Forecasting (WRF) model is used to investigate the radiative effect of dust on the development of AEWs during August and September, the months of maximum tropical cyclone activity, in years 2003-2007. The simulations show that dust radiative forcing enhances the convective instability of the environment. As a result, most AEWs intensify in the presence of a dust layer. The Lorenz energy cycle analysis reveals that the dust radiative forcing enhances the condensational heating, which elevates the zonal and eddy available potential energy. In turn, available potential energy is effectively converted to eddy kinetic energy, in which local convective overturning plays the primary role. The magnitude of the intensification effect depends on the initial environmental conditions, including moisture, baroclinity, and the depth of the boundary layer. We conclude that dust radiative forcing, albeit small, serves as a catalyst to promote local convection that facilitates AEW development.

Salinity effects on behavioural response to hypoxia in the non-native Mayan cichlid Cichlasoma urophthalmus from Florida Everglades wetlands.

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Schofield, P J; Loftus, W F; Fontaine, J A

2009-04-01

This study quantified the hypoxia tolerance of the Mayan cichlid Cichlasoma urophthalmus over a range of salinities. The species was very tolerant of hypoxia, using aquatic surface respiration (ASR) and buccal bubble holding when oxygen tensions dropped to <20 mmHg (c. 1.0 mg l(-1)) and 6 mmHg, respectively. Salinity had little effect on the hypoxia tolerance of C. urophthalmus, except that bubble holding was more frequent at the higher salinities tested. Levels of aggression were greatest at the highest salinity. The ASR thresholds of C. urophthalmus were similar to native centrarchid sunfishes from the Everglades, however, aggression levels for C. uropthalmus were markedly higher.

The first record of the invasive Asian fish tapeworm (Schyzocotyle acheilognathi from an endemic cichlid fish in Madagascar

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Scholz T.

2018-03-01

Full Text Available The Asian fish tapeworm, Schyzocotyle acheilognathi (Yamaguti, 1934 (Cestoda: Bothriocephalidea, is an invasive parasite of freshwater fishes that have been reported from more than 200 freshwater fish worldwide. It was originally described from a small cyprinid, Acheilognathus rombeus, in Japan but then has spread, usually with carp, minnows or guppies, to all continents including isolated islands such as Hawaii, Puerto Rico, Cuba or Sri Lanka. In the present account, we report the first case of the infection of a native cichlid fish, Ptychochromis cf. inornatus (Perciformes: Cichlidae, endemic to Madagascar, with S. acheilognathi. The way of introduction of this parasite to the island, which is one of the world’s biodiversity hotspots, is briefly discussed.

Dietary habits of juveniles of the Mayan cichlid, Cichlasoma urophthalmus, in mangrove ponds of an offshore islet in Belize, Central America

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Amandine Vaslet

Full Text Available Foraging habitats of juveniles of the Mayan cichlid, Cichlasoma urophthalmus (Günther, 1862, were investigated in two mangrove ponds located in Twin Cays offshore islet in Belize: Sink Hole pond (SH and Hidden Lake pond (HL. Sink Hole pond is a semiclosed body of water, whereas Hidden Lake pond is connected by a channel to adjacent seagrass beds that surround the islet. Gut contents of 21 juvenile C. urophthalmus (9.8-13.2 cm total length were analyzed, and five prey taxa were identified. In both mangrove ponds, C. urophthalmus were opportunistic carnivores and consumed primarily crustaceans. Plant material and detritus present in gut contents were most likely ingested incidentally when the fish foraged on small invertebrates. Carbon isotopic values of fish specimens from the two ponds were similar (mean ± SD of -19.2 ± 0.4‰ in SH and -19.4 ± 0.4‰ in HL, and were close to those of mangrove prey (mean ± SD = -20.2 ± 1.5‰, suggesting that this fish species forages in this habitat. Mixing models showed a higher contribution of mangrove food sources to the fish diet than seagrass food sources. This study reveals that young Mayan cichlids, inhabiting two Belize mangrove ponds, are generalists and opportunistic carnivores that forage on mangrove food sources and do not appear to move to adjacent seagrass beds to complement their diets. Understanding trophic linkages between aquatic consumers and food resources may contribute to better management of threatened coastal ecosystems.

Development of digestive enzymes in larvae of Mayan cichlid Cichlasoma urophthalmus.

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López-Ramírez, G; Cuenca-Soria, C A; Alvarez-González, C A; Tovar-Ramírez, D; Ortiz-Galindo, J L; Perales-García, N; Márquez-Couturier, G; Arias-Rodríguez, L; Indy, J R; Contreras-Sánchez, W M; Gisbert, E; Moyano, F J

2011-03-01

The development of digestive enzymes during the early ontogeny of the Mayan cichlid (Cichlasoma urophthalmus) was studied using biochemical and electrophoretic techniques. From yolk absorption (6 days after hatching: dah), larvae were fed Artemia nauplii until 15 dah, afterward they were fed with commercial microparticulated trout food (45% protein and 16% lipids) from 16 to 60 dah. Several samples were collected including yolk-sac larvae (considered as day 1 after hatching) and specimens up to 60 dah. Most digestive enzymes were present from yolk absorption (5-6 dah), except for the specific acid proteases activity (pepsin-like), which increase rapidly from 8 dah up to 20 dah. Three alkaline proteases isoforms (24.0, 24.8, 84.5 kDa) were detected at 8 dah using SDS-PAGE zymogram, corresponding to trypsin, chymotrypsin and probably leucine aminopeptidase enzymes, and only one isoform was detected (relative electromobility, Rf = 0.54) for acid proteases (pepsin-like) from 3 dah onwards using PAGE zymogram. We concluded that C. urophthamus is a precocious fish with a great capacity to digest all kinds of food items, including artificial diets provided from 13 dah.

Occurrence of Sciadicleithrum mexicanum Kritsky, Vidal-Martinez et Rodríguez-Canul, 1994 (Monogenea: Dactylogyridae) in the Cichlid Cichlasoma urophthalmus from a flooded quarry in Yucatan, Mexico

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Mendoza-Franco,E. F.; Vidal-Martínez,V.; Simá-Álvarez,R.; Rodríguez-Canul,R.; Vivas-Rodríguez,C.; Scholz,T.

1995-01-01

Cichlids, Cichlasoma urophthalmus, collected in a flooded quarry in the Yucatan Peninsula, Mexico, from January through June 1992, had high levels of infection with the ancyrocephaline Sciadicleithrum mexicanum (Monogena: Dactylogyridade) in all montlhly samples. Neither occurrence nor maturation of the worms eshibited any pronounced monthly fluctuation. The infection rate was found to be sizedependent, greater in longer fish. The worms occurred on primary lamellae of gill filaments of all ar...

South African Association of Physicists in Medicine and Biology: 26. annual congress

International Nuclear Information System (INIS)

1986-01-01

The twenty-sixth annual congress of the South African Association of Physicists in Medicine and Biology was held from 18-21 March 1986 in Pretoria. Papers delivered on the conference covered subjects like medical physics, radiotherapy, radiation protection, calibration of radiation monitors, radiation detectors, radiation doses and dosimetry

Differential Survival between Visual Environments Supports a Role of Divergent Sensory Drive in Cichlid Fish Speciation.

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Maan, Martine E; Seehausen, Ole; Groothuis, Ton G G

2017-01-01

Identifying the selective forces that initiate ecological speciation is a major challenge in evolutionary biology. Sensory drive has been implicated in speciation in various taxa, largely based on phenotype-environment correlations and signatures of selection in sensory genes. Here, we present a reciprocal transplant experiment revealing species differences in performance in alternative visual environments, consistent with speciation by divergent sensory drive. The closely related cichlids Pundamilia pundamilia and Pundamilia nyererei inhabit different visual environments in Lake Victoria and show associated differences in visual system properties. Mimicking the two light environments in the laboratory, we find a substantial reduction in survival of both species when reared in the other species' visual environment. This implies that the observed differences in Pundamilia color vision are indeed adaptive and substantiates the implicit assumption in sensory drive speciation models that divergent environmental selection is strong enough to drive divergence in sensory properties.

Strengthening African Union for African Integration: An African ...

African Journals Online (AJOL)

Log in or Register to get access to full text downloads. ... in the international state system and seek for African initiative in solving African problems. ... of the African Union by examining the efforts of African Leaders towards African integration, ...

Capillaria (Hepatocapillaria) cichlasomae (Nematoda: Capillariidae) from the liver of the cichlid fish Cichlasoma urophthalmus from Yucatan, Mexico.

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Moravec, F; Scholz, T; Mendoza Franco, E

1995-01-01

Capillaria (Hepatocapillaria) cichlasomae sp. n., parasitic in the liver of the cichlid Cichlasoma urophthalmus (Günther) from a small freshwater lake ("aguada") Xpoc in Yucatan, Mexico, is described. The parasite is characterized mainly by its small body size (male 1.8 mm, female 4.5 mm), the structure of the stichosome (markedly short stichocytes in one row) and the male (the presence of a pair of small subventral postanal papillae) and female (anus distinctly subterminal) caudal ends, and by the size and structure of the spicule (spicule 0.068-0.085 mm long, with marked transverse grooves on surface) and eggs (size 0.053-0.058 x 0.023 mm, with protruding polar plugs). This is the second known Capillaria species from the liver of fish and the first one from the liver of a freshwater fish.

Male mate choice scales female ornament allometry in a cichlid fish

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Kullmann Harald

2010-10-01

Full Text Available Abstract Background Studies addressing the adaptive significance of female ornamentation have gained ground recently. However, the expression of female ornaments in relation to body size, known as trait allometry, still remains unexplored. Here, we investigated the allometry of a conspicuous female ornament in Pelvicachromis taeniatus, a biparental cichlid that shows mutual mate choice and ornamentation. Females feature an eye-catching pelvic fin greatly differing from that of males. Results We show that allometry of the female pelvic fin is scaled more positively in comparison to other fins. The pelvic fin exhibits isometry, whereas the other fins (except the caudal fin show negative allometry. The size of the pelvic fin might be exaggerated by male choice because males prefer female stimuli that show a larger extension of the trait. Female pelvic fin size is correlated with individual condition, suggesting that males can assess direct and indirect benefits. Conclusions The absence of positive ornament allometry might be a result of sexual selection constricted by natural selection: fins are related to locomotion and thus may be subject to viability selection. Our study provides evidence that male mate choice might scale the expression of a female sexual ornament, and therefore has implications for the understanding of the relationship of female sexual traits with body size in species with conventional sex-roles.

Reproductive-tactic-specific variation in sperm swimming speeds in a shell-brooding cichlid.

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Fitzpatrick, J L; Desjardins, J K; Milligan, N; Montgomerie, R; Balshine, S

2007-08-01

Theory predicts that males experiencing elevated levels of sperm competition will invest more in gonads and produce faster-swimming sperm. Although there is ample evidence in support of the first prediction, few studies have examined sperm swimming speed in relation to sperm competition. In this study, we tested these predictions from sperm competition theory by examining sperm characteristics in Telmatochromis vittatus, a small shell-brooding cichlid fish endemic to Lake Tanganyika. Males exhibit four different reproductive tactics: pirate, territorial, satellite, and sneaker. Pirate males temporarily displace all other competing males from a shell nest, whereas sneaker males always release sperm in the presence of territorial and satellite males. Due to the fact that sneakers spawn in the presence of another male, sneakers face the highest levels of sperm competition and pirates the lowest, whereas satellites and territorials experience intermediate levels. In accordance with predictions, sperm from sneakers swam faster than sperm from males adopting the other reproductive tactics, whereas sperm from pirates was slowest. Interestingly, we were unable to detect any variation in sperm tail length among these reproductive tactics. Thus, sperm competition appears to have influenced sperm energetics in this species without having any influence on sperm size.

Influence of watershed activities on the water quality and fish assemblages of a tropical African reservoir.

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Mustapha, Moshood K

2009-09-01

Agricultural and fisheries activities around the watershed of an African tropical reservoir (Oyun reservoir, Offa, Nigeria) were found to contribute significantly to water quality deterioration of the dam axis of the reservoir, leading to eutrophication of that part of the reservoir. This is evident from the high amount of nitrate (6.4 mg/l), phosphate (2.2 mg/l) and sulphate (16.9 mg/l) in the water body which was higher than most other reservoirs in Nigeria. These nutrients originate in fertilizer run-offs from nearby farmlands and were found in higher concentrations in the rainy season which is usually the peak of agricultural activities in the locality. The eutrophication was more pronounced on the dam axis because it is the point of greatest human contact where pressure and run-off of sediments were high. The eutrophication altered the food web cycle which consequently affected the fish species composition and abundance with the dominance of cichlids (planktivorous group) and decline of some species in the fish population. Best management practices (BMP) to control and reduce the eutrophication and improve water quality and fish assemblages should be adopted and adapted to suit the situation in the reservoir.

Need for cooperation among IRPA associate societies in African

International Nuclear Information System (INIS)

Mustapha, A.O.

2010-01-01

Radiation is an inescapable part of the natural environment, and it is also produced artificially for a variety of unique applications in health, environmental studies, industry, etc. Our present and future lifestyles are unsustainable without peaceful applications of radiation technologies. Events around the world continue to indicate an increasing need for nuclear energy. Africa: A high level African Regional Conference on the contribution of Nuclear Energy to Peace and Sustainable Development (January 2007, Algiers), recommended that African countries should promote the acquisition of scientific know-how and the necessary infrastructure for the peaceful use of nuclear energy. This recommendation was adopted by the Executive council of Ministers during the 8th African Union (AU) summit of January 2007. 6 Many countries in Africa have established nuclear energy and radiation facilities for research and applications in many fields, including Agriculture, Medicine, Security, Industry, etc. There is now a new Nuclear power renaissance in Africa. However, in order to derive the full benefits of nuclear energy and radiation technologies, certain protective measures must be established and used correctly Radiation Protection. Radiation Protection in Africa .. At various stages of development, but generally: While the use of ionizing radiation is advancing in many countries in Africa, this is not accompanied by a corresponding effort to ensure radiation protection Constraints: Inadequacies in government support e.g. legislation, training and education; radiation protection infrastructures; Lack of radiation protection professionalism e.g. network and cooperation among RP Professionals and between them and other stakeholders; etc. Some of the pressing needs Strengthening RP infrastructures in Africa; Establishing effective and sustainable cooperation and networks among RP professionals (flow of RP information); Interacting with other stakeholders (governmental

Infection by anisakid nematodes contracaecum spp. in the Mayan cichlid fish 'Cichlasoma (Nandopsis)' urophthalmus (Gunther 1862).

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Bergmann, Gaddy T; Motta, Philip J

2004-04-01

Larval nematodes that parasitize the Mayan cichlid fish 'Cichlasoma (Nandopsis)' urophthalmus (Günther 1862) in southern Florida were identified as Contracaecum spp. (Nematoda: Anisakidae, Anisakinae). The objective of this study was to determine whether infection intensity and prevalence of these parasites differ between a brackish water and freshwater habitat or through ontogeny in the freshwater habitat only. The nematodes were removed from the abdominal cavity of the fishes and counted. Infection intensity was compared between habitats using analysis of covariance and evaluated through ontogeny using Spearman rank order correlation. Prevalence was compared between habitats and between adults and juveniles from the freshwater habitat using a z-test. Although infection intensity did not differ between habitats, infection prevalence was greater at the freshwater site (FWS). Both the prevalence and intensity of nematode infection increased through ontogeny at the FWS, and no nematode was found in fishes that were smaller than 93 mm standard length. Thus, the parasites appear to accumulate during the lifetime of the fishes.

Evolutionary relationships in the sand-dwelling cichlid lineage of lake tanganyika suggest multiple colonization of rocky habitats and convergent origin of biparental mouthbrooding.

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Koblmüller, Stephan; Salzburger, Walter; Sturmbauer, Christian

2004-01-01

The cichlid species flock of Lake Tanganyika is comprised of seven seeding lineages that evolved in step with changes of the lake environment. One seeding lineage diversified into at least six lineages within a short period of time. Our study focuses on the diversification of one of these lineages, the Ectodini, comprising highly specialized, sand- and rock-dwelling species. They display two distinct breeding styles: maternal and biparental mouthbrooding. By analyzing three mtDNA gene segments in 30 species representing all 13 described genera, we show that the Ectodini rapidly diversified into four clades at the onset of their radiation. The monotypic genus Grammatotria is likely to represent the most ancestral split, followed by the almost contemporary origin of three additional clades, the first comprising the benthic genus Callochromis, the second comprising the benthic genera Asprotilapia, Xenotilapia, Enantiopus, and Microdontochromis, and the third comprising the semi-pelagic genera Ophthalmotilapia, Cardiopharynx, Cyathopharynx, Ectodus, Aulonocranus, Lestradea, and Cunningtonia. Our study confirms the benthic and sand-dwelling life-style as ancestral. Rocky habitats were colonized independently in the Xenotilapia- and Ophthalmotilapia-clade. The Xenotilapia-clade comprises both maternal and biparental mouthbrooders. Their mode of breeding appears to be highly plastic: biparental mouthbrooding either evolved once in the common ancestor of the clade, to be reverted at least three times, or evolved at least five times independently from a maternally mouthbrooding ancestor. Furthermore, the genera Xenotilapia, Microdontochromis, Lestradea, and Ophthalmotilapia appeared paraphyletic in our analyses, suggesting the need of taxonomic revision.

Hierarchical structure of ecological and non-ecological processes of differentiation shaped ongoing gastropod radiation in the Malawi Basin.

Science.gov (United States)

Van Bocxlaer, Bert

2017-09-13

Ecological processes, non-ecological processes or a combination of both may cause reproductive isolation and speciation, but their specific roles and potentially complex interactions in evolutionary radiations remain poorly understood, which defines a central knowledge gap at the interface of microevolution and macroevolution. Here I examine genome scans in combination with phenotypic and environmental data to disentangle how ecological and non-ecological processes contributed to population differentiation and speciation in an ongoing radiation of Lanistes gastropods from the Malawi Basin. I found a remarkable hierarchical structure of differentiation mechanisms in space and time: neutral and mutation-order processes are older and occur mainly between regions, whereas more recent adaptive processes are the main driver of genetic differentiation and reproductive isolation within regions. The strongest differentiation occurs between habitats and between regions, i.e. when ecological and non-ecological processes act synergistically. The structured occurrence of these processes based on the specific geographical setting and ecological opportunities strongly influenced the potential for evolutionary radiation. The results highlight the importance of interactions between various mechanisms of differentiation in evolutionary radiations, and suggest that non-ecological processes are important in adaptive radiations, including those of cichlids. Insight into such interactions is critical to understanding large-scale patterns of organismal diversity. © 2017 The Author(s).

Black carbon and West African Monsoon precipitation. Observations and simulations

International Nuclear Information System (INIS)

Huang, J.; Adams, A.; Zhang, C.; Wang, C.

2009-01-01

We have recently investigated large-scale co-variability between aerosol and precipitation and other meteorological variables in the West African Monsoon (WAM) region using long term satellite observations and reanalysis data. In this study we compared the observational results to a global model simulation including only direct radiative forcing of black carbon (BC). From both observations and model simulations we found that in boreal cold seasons anomalously high African aerosols are associated with significant reductions in cloud amount, cloud top height, and surface precipitation. These results suggest that the observed precipitation reduction in the WAM region is caused by radiative effect of BC. The result also suggests that the BC effect on precipitation is nonlinear. (orig.)

Partial characterisation of digestive proteases of the Mayan cichlid Cichlasoma urophthalmus.

Science.gov (United States)

Cuenca-Soria, C A; Álvarez-González, C A; Ortiz-Galindo, J L; Nolasco-Soria, H; Tovar-Ramírez, D; Guerrero-Zárate, R; Castillo-Domínguez, A; Perera-García, M A; Hernández-Gómez, R; Gisbert, E

2014-06-01

The characterisation of digestive proteases in native freshwater fish such as the Mayan cichlid Cichlasoma urophthalmus provides scientific elements that may be used to design balanced feed that matches with the digestive capacity of the fish. The purpose of this study was to characterise the digestive proteases, including the effect of the pH and the temperature on enzyme activity and stability, as well as the effect of inhibitors using multienzymatic extracts of the stomach and intestine of C. urophthalmus juveniles. Results showed that the optimum activities of the acid and alkaline proteases occurred at pH values of 3 and 9, respectively, whereas their optimum temperatures were 55 and 65 °C, respectively. The acid proteases were most stable at pH values of 2–3 and at temperatures of 35–45 °C, whereas the alkaline proteases were most stable at pH values of 6–9 and at 25–55 °C. The inhibition assays recorded a residual activity of 4% with pepstatin A for the acid proteases. The inhibition of the alkaline proteases was greater than 80% with TPCK, TLCK, EDTA and ovalbumin, and of 60 and 43.8% with PMSF and SBT1, respectively. The results obtained in this study make it possible to state that C. urophthalmus has a sufficiently complete digestive enzyme machinery to degrade food items characteristic of an omnivorous fish species, although specimens showed a tendency to carnivory.

Redirected aggression as a conflict management tactic in the social cichlid fish Julidochromis regani.

Science.gov (United States)

Ito, Munehiko H; Yamaguchi, Motoomi; Kutsukake, Nobuyuki

2018-01-31

Conflict management consists of social behaviours that reduce the costs of conflict among group members. Redirected aggression-that is, when a recently attacked individual attacks a third party immediately after the original aggression-is considered a conflict management tactic, as it may reduce the victim's probability of being the object of further aggression. Redirected aggression has been reported in many vertebrates, but few quantitative studies have been conducted on this behaviour in fishes. We examined the function of redirected aggression in Julidochromis regani , a social cichlid fish. Behavioural experiments showed that redirected aggression functioned to divert the original aggressor's attention towards a third party and to pre-empt an attack towards the victim by the third-party individual, specifically among females. We found, however, that redirected aggression did not delay the recurrence of aggression by the original aggressor. These results suggest that a primary function of redirected aggression is to maintain the dominance of its actor against a subordinate occupying an adjacent rank. This study provides, to our knowledge, the first evidence that redirected aggression functions to manage conflict in social fish. © 2018 The Author(s).

Radiation induced changes in the airway - anaesthetic implications

African Journals Online (AJOL)

Adele

CASE REPORT. Southern African Journal of Anaesthesia & Analgesia - May 2004. 19. Radiation ... Summary: Radiation induces a variety of changes in the airway that can potentially lead to difficult intubation. ... Mask holding and ventilation is.

A cost-effective technique for integrating personal radiation dose assessment with personal gravimetric sampling

International Nuclear Information System (INIS)

Strydom, R.; Rolle, R.; Van der Linde, A.

1992-01-01

During recent years there has been an increasing awareness internationally of radiation levels in the mining and milling of radioactive ores, including those from non-uranium mines. A major aspect of radiation control is concerned with the measurement of radiation levels and the assessment of radiation doses incurred by individual workers. Current techniques available internationally for personnel monitoring of radiation exposures are expensive and there is a particular need to reduce the cost of personal radiation monitoring in South African gold mines because of the large labour force employed. In this regard the obvious benefits of integrating personal radiation monitoring with existing personal monitoring systems already in place in South African gold mines should be exploited. A system which can be utilized for this purpose is personal gravimetric sampling. A new cost-effective technique for personal radiation monitoring, which can be fully integrated with the personal gravimetric sampling strategy being implemented on mines, has been developed in South Africa. The basic principles of this technique and its potential in South African mines are described. 9 refs., 7 figs

The correlation between subordinate fish eye colour and received attacks: a negative social feedback mechanism for the reduction of aggression during the formation of dominance hierarchies.

Science.gov (United States)

Miyai, Caio A; Carretero Sanches, Fábio H; Costa, Tânia M; Colpo, Karine Delevati; Volpato, Gilson L; Barreto, Rodrigo E

2011-12-01

Eye darkening has been linked to social status in fish. The subordinate's eyes darken, while the eyes of the dominant fish become pale. Although this phenomenon has been described in salmonid fishes and in the African cichlid Nile tilapia Oreochromis niloticus, it is unclear whether eye darkening correlates with a reduction in aggressive behaviour. Thus, we evaluated the link between social status and eye darkening. We evaluated whether the eye colours of subordinate fish correlate with the frequency of received attacks in a neotropical fish, the pearl cichlid Geophagus brasiliensis. We paired pearl cichlids and quantified both the aggressive behaviour and the eye darkening of each fish. As has been described for Nile tilapia and Atlantic salmon, a clear-cut hierarchical relationship formed, where dominance and subordination were associated with pale and dark eye colours, respectively. Initially, eye colour darkening was positively correlated with the frequency of received attacks; however, a negative association occurred following eye darkening, in which the intensity of aggressive interactions decreased. Thus, fish that initially received a high number of attacks signalled subordination more rapidly and intensely (rapid and dramatic eye darkening), thereby inducing a negative social feedback mechanism that led to reduced aggression. Copyright © 2011 Elsevier GmbH. All rights reserved.

Two new species of zooplanktivorous haplochromine cichlids from Lake Victoria, Tanzania

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Marnix de Zeeuw

2013-01-01

Full Text Available Two new species of zooplanktivorous haplochromine cichlids from Lake Victoria, Tanzania, are described and illustrated. These species closely resemble each other. Their affinities to other zooplanktivorous haplochromines from Lake Victoria are discussed. Haplochromis argens sp. n., which featured under nicknames (mainly H. “argens” in more than 50 papers, was caught both in the Mwanza Gulf and the Emin Pasha Gulf, whereas H. goldschmidti sp. n. was only found in the Emin Pasha Gulf. Of the latter species only males are available, but it seems unlikely that it represents a case of male colour polymorphism as several presumably unrelated characters differ in sympatry between the two species, suggesting that there is no gene flow. Statistical analysis revealed that the overall difference between the two species is greater than that between the populations from the two locations. Body depth of the two species in sympatry in the Emin Pasha Gulf was more similar than that of H. goldschmidti sp. n. and the allopatric population of H. argens sp. n. from the Mwanza Gulf, which may indicate an overall environmental effect. However, several measurements related to the width of snout and mouth differed more between the populations of the two species in sympatry than between the allopatric populations. In contrast to a group of zooplanktivorous species that recovered successfully after environmental changes in the lake, H. argens sp. n. is among a group that became extremely rare and probably is in danger of extinction; the conservation status of H. goldschmidti sp. n. is currently unknown.

Mesoscale Modeling of Smoke Particles Distribution and Their Radiative Feedback over Northern Sub-Saharan African Region

Science.gov (United States)

Yue, Y.; Wang, J.; Ichoku, C. M.; Ellison, L.

2015-12-01

Stretching from southern boundary of Sahara to the equator and expanding west to east from Atlantic Ocean coasts to the India Ocean coasts, the northern sub-Saharan African (NSSA) region has been subject to intense biomass burning. Comprised of savanna, shrub, tropical forest and a number of agricultural crops, the extensive fires burn belt covers central and south of NSSA during dry season (from October to March) contributes to one of the highest biomass burning rate per km2 in the world. Due to smoke particles' absorption effects of solar radiation, they can modify the surface and atmosphere temperature and thus change atmospheric stability, height of the boundary layer, regional atmospheric circulation, evaporation rate, cloud formation, and precipitation. Hence, smoke particles emitted from biomass burning over NSSA region has a significant influence to the air quality, weather and climate variability. In this study, the first version of this Fire Energetics and Emissions Research (FEER.v1) emissions of several smoke constituents including light-absorbing organic carbon (OC) and black carbon (BC) are applied to a state-of-science meteorology-chemistry model as NOAA Weather Research and Forecasting Model with Chemistry (WRF-Chem). We analyzed WRF-Chem simulations of surface and vertical distribution of various pollutants and their direct radiative effects in conjunction with satellite observation data from Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar data with Orthogonal Polarization (CALIPSO) to strengthen the importance of combining space measured emission products like FEER.v1 emission inventory with mesoscale model over intense biomass burning region, especially in area where ground-based air-quality and radiation-related observations are limited or absent.

An overview of the Gyrodactylus (Monogenea: Gyrodactylidae) species parasitizing African catfishes, and their morphological and molecular diversity

Czech Academy of Sciences Publication Activity Database

Přikrylová, I.; Blažek, Radim; Vanhove, M. P. M.

2012-01-01

Roč. 110, č. 3 (2012), s. 1185-1200 ISSN 0932-0113 R&D Projects: GA MŠk LC522 Institutional research plan: CEZ:AV0Z60930519 Keywords : Monogenea * South Africa * Lake Tanganyika * Cichlid fishes Subject RIV: EG - Zoology Impact factor: 2.852, year: 2012

Strengthening Regulatory Cooperation in Africa: Lessons Learned from the African Regulatory Network (FNRBA)

International Nuclear Information System (INIS)

Severa, R.

2016-01-01

Africa is a continent endowed in mineral resources. Among others, there are vast deposits of gold and uranium in African countries. The by-products of these minerals are in some cases radioactive and therefore exposures must be monitored. Additionally, Africa uses a lot of radioactive sources in different industries and in the health sector. Regulation of these mining activities and facilities handling these radioactive sources becomes extremely important for the protection of people, property and the environment against harmful effects of ionizing radiation. Due to the vast size of the African continent, with inequitable resources, regional cooperation becomes key to capacity building and knowledge and information sharing. In order to achieve this, African Member States resolved to form a Forum for Nuclear Regulatory Bodies in Africa (FNRBA) in 2009. The paper will present the FNRBA, its activities, achievements and challenges in the quest to bring about effective regulation of nuclear and radiation safety in the continent. (author)

A desk evaluation review of project RAF/9/005 radiation protection development. Project desk evaluation

International Nuclear Information System (INIS)

1994-01-01

The Agency has been assisting member nations through a number of national TC projects in radiation protection and related areas over the years. In addition, a regional project RAF/9/005 - Radiation Protection Development (which is under this review) was approved in 1988, with the aim of assessing existing radiation protection practices in the African Member States in relation to the Agency's new basic safety standards for radiation protection, and to advise Governments on improvements. The project was subsequently extended up to 1994 as an umbrella project to assist all African Member States in the development of appropriate radiation protection services; to co-ordinate the implementation of the relevant national TC projects; and to develop co-operation amongst groups of Member States on a regional and sub-regional basis. Particular emphasis was to be given to manpower development through workshops, seminars and training courses in radiation protection and safety. In parallel thereto, the Agency's Radiation Protection Advisory Teams (RAPATs) visited nineteen African Member States during the period 1986 through 1993, to review and assess their radiation protection activities, identify priorities, and design long-term radiation protection programmes. RAPAT findings and recommendations were considered in drawing up programmes for implementation under project RAF/9/005

African Journals Online: Central African Republic

African Journals Online (AJOL)

African Journals Online: Central African Republic. Home > African Journals Online: Central African Republic. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This ...

Stress axis regulation during social ascension in a group-living cichlid fish.

Science.gov (United States)

Culbert, Brett M; Gilmour, Kathleen M; Balshine, Sigal

2018-06-19

Animals living in groups often form social hierarchies, with characteristic behaviours and physiologies associated with rank. However, when social opportunities arise and a subordinate ascends into a dominant position, quick adjustments are necessary to secure this position. Such periods of social transition are typically associated with elevated glucocorticoid production, but the precise regulation of the stress axis during these occasions is not well understood. Using the group-living cichlid, Neolamprologus pulcher, the effects of social ascension on the stress axis were assessed. Ascenders rapidly filled experimentally created vacancies, adopting a dominant behavioural phenotype within 72 h-elevating aggression, activity, and workload, while receiving high rates of affiliative behaviours from their group members. Despite assuming behavioural dominance within their groups, ascenders displayed higher cortisol levels than dominants three days post-ascension. Additionally, compared to subordinates, ascenders had increased transcript abundance of steroidogenic acute regulatory protein (star) and cytochrome p450 side-chain cleavage enzyme (p450scc) in the head kidney, indicating activation of the stress axis. Cortisol levels were lowest in ascenders that displayed low rates of aggression, potentially reflecting the reestablishment of social stability in these groups. Increased transcript abundance of both glucocorticoid receptors (gr1 and gr2) in the brain's preoptic area (POA) of ascenders compared to dominants suggested an enhanced capacity for cortisol regulation via negative feedback. Our results reveal a regulatory cascade of behavioural and physiological interactions and highlight the importance of investigating the underlying mechanisms regulating the stress axis. Copyright © 2018. Published by Elsevier Inc.

Ecology and life history of an Amazon floodplain cichlid: the discus fish Symphysodon (Perciformes: Cichlidae

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William G. R. Crampton

Full Text Available The discus fishes of the genus Symphysodon are popular ornamental cichlids that occur in floodplain lakes and flooded forests of the lowland Amazon Basin. These habitats are characterized by extreme seasonal fluctuations in the availability of food, shelter and dissolved oxygen, and also the densities of predators and parasites. Most aspects of discus biology are influenced by these fluctuating conditions. This paper reports an autoecological study of the western Amazonian discus S. haraldi (until recently classified as S. aequifasciatus. This species feeds predominantly on algal periphyton, fine organic detritus, plant matter, and small aquatic invertebrates. At high water it forages alone or in small groups in flooded forests. At low water it forms large aggregations in fallen tree crowns along lake margins. Breeding occurs at the beginning of the flood season, ensuring that the progeny are well grown before the next low water period. Symphysodon haraldi is an iteroparous partial spawner, reaches reproductive maturity within a year, and undertakes parental care of its eggs and larvae. The timing of spawning events, and/or the rate of brood survival, may be influenced by fluctuations in the flood level, resulting in a non-unimodal distribution of size classes for the subsequent 1+ cohort.

Parsing the Gulf between Africans and African Americans

Directory of Open Access Journals (Sweden)

Ashly Nsangou

2018-02-01

Full Text Available The rise in African immigrants to the US provides an opportunity to assess relations between Africans and African Americans in college. An online survey of 322 current and recently-graduated college students (including 45 Africans, 160 African Americans, and 117 whites assessed respondents’ experiences of racism in US high schools and colleges. Semi-structured interviews of 30 students (10 African, 10 African American and 10 white students supplemented these data. Even within a sociopolitical context of more visible racial intolerance, Black intra-racial cohesion was absent. Although more first- and second-generation Africans (73% felt that they had been judged while living in the US compared to African Americans (34% or whites (20%, for 70–80% of respondents, this had occurred only in high school. Despite experiencing these judgments, Africans’ identity related more to their focus on education than their race, reflected in a higher proportion who felt intense family pressure to attend college (65% compared to African Americans (37% and whites (39%. Interview data confirmed previous reports in the literature that African Americans lack a sense of connection to Africans, attributed to Africans’ purported sense of superiority and disregard for African Americans’ ongoing struggle to end oppression. These mixed-methods data suggest that intermingling in the college environment has not resulted in first- and second-generation Africans and African Americans sharing a common in-group, race-based identity. We discuss the implications of overlooking ethnic distinctions due to presumptions of racial homogeneity that deprive Black individuals of their uniqueness.

Experimental Infection of the Mayan Cichlid Cichlasoma urophthalmus with the Oomycete Aphanomyces invadans.

Science.gov (United States)

Aguirre-Ayala, Daniel; Vidal-Martínez, Víctor Manuel

2015-08-01

This study aimed to determine the susceptibility of the Mayan cichlid Cichlasoma urophthalmus to infection with the fungus Aphanomyces invadans (also known as epizootic ulcerative syndrome [EUS]). A total of 27 C. urophthalmus were exposed to the original A. Invadans 2006/86/EC strain by intramuscularly injecting the fish with 25,000 zoospores/ml or exposing the fish to a suspension of 25,000 zoospores/ml in 6-L aquaria for 30 days. To assess the infectious capacity of A. invadans, 3 golden barbs (Puntius semifasciolatus) were infected intramuscularly with 200,000 zoospores/ml. A second experiment using 100 C. urophthalmus was performed for 60 days with 50 fish in each treatment group. A polymerase chain reaction (PCR)-based diagnostic method was used; muscle and gills were the target tissues. In the first experiment, none of the exposed C. urophthalmus developed skin lesions related to A. invadans infection. However, PCR analysis revealed that infection had occurred. For the intramuscular treatment, there were significant differences between the controls and the muscle samples (Fisher's exact test; P 0.05). All golden barbs became infected, as indicated by PCR, and developed skin lesions typical of A. invadans infection. We concluded that C. urophthalmus was infected with A. invadans but was an asymptomatic carrier because skin lesions did not develop. In the second experiment, all fish were negative, suggesting that the fish had cleared the infection by the end of the experiment.

Evolution of feeding specialization in Tanganyikan scale-eating cichlids: a molecular phylogenetic approach

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Nishida Mutsumi

2007-10-01

Full Text Available Abstract Background Cichlid fishes in Lake Tanganyika exhibit remarkable diversity in their feeding habits. Among them, seven species in the genus Perissodus are known for their unique feeding habit of scale eating with specialized feeding morphology and behaviour. Although the origin of the scale-eating habit has long been questioned, its evolutionary process is still unknown. In the present study, we conducted interspecific phylogenetic analyses for all nine known species in the tribe Perissodini (seven Perissodus and two Haplotaxodon species using amplified fragment length polymorphism (AFLP analyses of the nuclear DNA. On the basis of the resultant phylogenetic frameworks, the evolution of their feeding habits was traced using data from analyses of stomach contents, habitat depths, and observations of oral jaw tooth morphology. Results AFLP analyses resolved the phylogenetic relationships of the Perissodini, strongly supporting monophyly for each species. The character reconstruction of feeding ecology based on the AFLP tree suggested that scale eating evolved from general carnivorous feeding to highly specialized scale eating. Furthermore, scale eating is suggested to have evolved in deepwater habitats in the lake. Oral jaw tooth shape was also estimated to have diverged in step with specialization for scale eating. Conclusion The present evolutionary analyses of feeding ecology and morphology based on the obtained phylogenetic tree demonstrate for the first time the evolutionary process leading from generalised to highly specialized scale eating, with diversification in feeding morphology and behaviour among species.

Incipient sympatric speciation in Midas cichlid fish from the youngest and one of the smallest crater lakes in Nicaragua due to differential use of the benthic and limnetic habitats?

Science.gov (United States)

Kautt, Andreas F; Machado-Schiaffino, Gonzalo; Torres-Dowdall, Julian; Meyer, Axel

2016-08-01

Understanding how speciation can occur without geographic isolation remains a central objective in evolutionary biology. Generally, some form of disruptive selection and assortative mating are necessary for sympatric speciation to occur. Disruptive selection can arise from intraspecific competition for resources. If this competition leads to the differential use of habitats and variation in relevant traits is genetically determined, then assortative mating can be an automatic consequence (i.e., habitat isolation). In this study, we caught Midas cichlid fish from the limnetic (middle of the lake) and benthic (shore) habitats of Crater Lake Asososca Managua to test whether some of the necessary conditions for sympatric speciation due to intraspecific competition and habitat isolation are given. Lake As. Managua is very small (Midas cichlids, Amphilophus tolteca. We found that fish from the limnetic habitat were more elongated than fish collected from the benthic habitat, as would be predicted from ecomorphological considerations. Stable isotope analyses confirmed that the former also exhibit a more limnetic lifestyle than the latter. Furthermore, split-brood design experiments in the laboratory suggest that phenotypic plasticity is unlikely to explain much of the observed differences in body elongation that we observed in the field. Yet, neutral markers (microsatellites) did not reveal any genetic clustering in the population. Interestingly, demographic inferences based on RAD-seq data suggest that the apparent lack of genetic differentiation at neutral markers could simply be due to a lack of time, as intraspecific competition may only have begun a few hundred generations ago.

Effect of mate size on maternal reproductive effort in the convict cichlid Amatitlania siquia

Institute of Scientific and Technical Information of China (English)

Ashley R. ROBART

2012-01-01

The differential allocation hypothesis predicts individuals will increase their reproductive investment when mated to a high quality partner.In many species of fish with biparental care females prefer large males due to the males' greater ability to raise more offspring to independence.I examined the relationship between mate quality,parental care and number of offspring in a natural population of convict cichlids Amatitlania siquia.The frequency of frontal displays by females was positively correlated with male standard length.Additionally,as males increased in length relative to their mate,females increased the frequency of chases towards predators,while males decreased the number of displays towards brood predators.This trade-off in parental effort within a pair due to mate quality is a key prediction of differential allocation.The number of offspring was correlated with male,but not female,standard length.These results support the differential allocation hypothesis in that females offered more parental care to offspring of a larger male,while their mates decreased the amount of care they provided.Additionally,females benefited in terms of number of offspring by pairing with higher quality mates.Increased female investment may provide an incentive to ensure male care and maintain pair bonding,which could lead to greater reproductive success through increased offspring survival [Current Zoology 58 (1):66-72,2012].

Effect of mate size on maternal reproductive effort in the convict cichlid Amatitlania siquia

Directory of Open Access Journals (Sweden)

Ashley R. ROBART

2012-02-01

Full Text Available The differential allocation hypothesis predicts individuals will increase their reproductive investment when mated to a high quality partner. In many species of fish with biparental care females prefer large males due to the males’ greater ability to raise more offspring to independence. I examined the relationship between mate quality, parental care and number of offspring in a natural population of convict cichlids Amatitlania siquia. The frequency of frontal displays by females was positively correlated with male standard length. Additionally, as males increased in length relative to their mate, females increased the frequency of chases towards predators, while males decreased the number of displays towards brood predators. This trade-off in parental effort within a pair due to mate quality is a key prediction of differential allocation. The number of offspring was correlated with male, but not female, standard length. These results support the differential allocation hypothesis in that females offered more parental care to offspring of a larger male, while their mates decreased the amount of care they provided. Additionally, females benefited in terms of number of offspring by pairing with higher quality mates. Increased female investment may provide an incentive to ensure male care and maintain pair bonding, which could lead to greater reproductive success through increased offspring survival [Current Zoology 58 (1: 66–72, 2012].

Biology of Crassicutis cichlasomae, a parasite of cichlid fishes in Mexico and Central America.

Science.gov (United States)

Scholz, T; Pech-Ek, M C; Rodriguez-Canul, R

1995-03-01

Field study on the biology of Crassicutis cichlasomae Manter, 1936 (Digenea: Homalometridae) was carried out in a small swamp in a limestone factory near Mérida, Yucatán, Mexico. Aquatic snails, Littorina (Littoridinopis) angulifera, harbouring C. cichlasomae rediae, cercariae and metacercariae, served both as the first and second intermediate hosts. Feeding experiments confirmed the conspecificity of metacercariae from naturally infected snails with adults from naturally infected fish. Gravid C. cichlasomae worms were obtained from experimentally infected fish 19 days post exposure at 22-24 degrees C. Examination of fish from the swamp in Mitza and other localities in the Yucatan Peninsula showed that the cichlids Cichlasoma urophthalmus and C. meeki were definitive hosts of C. cichlasomae. There was no pronounced preference of C. cichlasomae adults for the site of their location in the intestine of the definitive host; a slightly higher proportion (41%) of worms was only found in the anterior third of the gut. The time of miracidium development varied from 18.5 to 27.5 days; different temperature (20.1-35.7 degrees C) or light/darkness regimes influenced only slightly the rate of embryonic development, with shorter development times at higher temperature (34.8-35.7 degrees C) and constant darkness and/or light. With the exception of the sporocyst, all developmental stages are described and figured.

Aerosol interactions with African/Atlantic climate dynamics

International Nuclear Information System (INIS)

Hosseinpour, F; Wilcox, E M

2014-01-01

Mechanistic relationships exist between variability of dust in the oceanic Saharan air layer (OSAL) and transient changes in the dynamics of Western Africa and the tropical Atlantic Ocean. This study provides evidence of possible interactions between dust in the OSAL region and African easterly jet–African easterly wave (AEJ–AEW) system in the climatology of boreal summer, when easterly wave activity peaks. Synoptic-scale changes in instability and precipitation in the African/Atlantic intertropical convergence zone are correlated with enhanced aerosol optical depth (AOD) in the OSAL region in response to anomalous 3D overturning circulations and upstream/downstream thermal anomalies at above and below the mean-AEJ level. Upstream and downstream anomalies are referred to the daily thermal/dynamical changes over the West African monsoon region and the Eastern Atlantic Ocean, respectively. Our hypothesis is that AOD in the OSAL is positively correlated with the downstream AEWs and negatively correlated with the upstream waves from climatological perspective. The similarity between the 3D pattern of thermal/dynamical anomalies correlated with dust outbreaks and those of AEWs provides a mechanism for dust radiative heating in the atmosphere to reinforce AEW activity. We proposed that the interactions of OSAL dust with regional climate mainly occur through coupling of dust with the AEWs. (paper)

African Journals Online: African Studies

African Journals Online (AJOL)

Items 51 - 56 of 56 ... Research Review of the Institute of African Studies. Please note: As of 2013 the Research Review of the Institute of African Studies is now publishing under the title Contemporary Journal of African Studies. You can view the CJAS pages on AJOL here: http://www.ajol.info/index.php/contjas/index.

Black versus Black: The Relationship among African, African American, and African Caribbean Persons.

Science.gov (United States)

Jackson, Jennifer V.; Cothran, Mary E.

2003-01-01

Surveyed people of African descent regarding relationships among African, African-American, and African-Caribbean persons, focusing on contact and friendship, travel to countries of the diaspora, cross-cultural communication, thoughts and stereotypes, and education. Most respondents had contacts with the other groups, but groups had preconceived…

An overview of the facilities of the Ionizing Radiation Laboratory, South Africa

International Nuclear Information System (INIS)

Mostert, J.C.

2002-01-01

The Ionising Radiation Laboratory (IRL) of the CSIR-National Metrology Laboratory (NML) in South Africa was recently accepted as a member of the IAEA SSDL network. This article gives a very brief overview of the services and facilities provided by this laboratory. The NML has the responsibility to realize and maintain the national measuring standards in South Africa. In the field of ionizing radiation, this function is performed by the IRL. The IRL provides traceability through its calibration and measurement services for regulatory authorities, institutions providing radiation therapy services such as hospitals and other oncology centres, radiation protection service providers such as the South African Bureau of Standards (SABS), the radiation protection industry in general and to companies providing industrial quality assurance services. These services also extend to a number of countries in the Southern African Development Community (SADC) which do not currently have metrology facilities of their own

Short-duration exposure to 2.45 GHz microwave radiation induces ...

African Journals Online (AJOL)

... disorganization in the testis of exposed group with increasing SARs. These results suggest that MW radiation has the potential to affect both male and female fertility adversely. Keywords: 2.45 GHz microwave radiation, histopathology, DNA single strand break, ovary, testis. African Journal of Biotechnology Vol. 12(2), pp.

Acquisition of Lateralized Predation Behavior Associated with Development of Mouth Asymmetry in a Lake Tanganyika Scale-Eating Cichlid Fish.

Directory of Open Access Journals (Sweden)

Yuichi Takeuchi

Full Text Available The scale-eating cichlid Perissodus microlepis with asymmetric mouth is an attractive model of behavioral laterality: each adult tears off scales from prey fishes' left or right flanks according to the direction in which its mouth is skewed. To investigate the development of behavioral laterality and mouth asymmetry, we analyzed stomach contents and lower jaw-bone asymmetry of various-sized P. microlepis (22 ≤ SL<115 mm sampled in Lake Tanganyika. The shapes of the pored scales found in each specimen's stomach indicated its attack side preference. Early-juvenile specimens (SL<45 mm feeding mainly on zooplankton exhibited slight but significant mouth asymmetry. As the fish acquired scale-eating (45 mm ≤ SL, attack side preference was gradually strengthened, as was mouth asymmetry. Among size-matched individuals, those with more skewed mouths ate more scales. These findings show that behavioral laterality in scale-eating P. microlepis is established in association with development of mouth asymmetry which precedes the behavioral acquisition, and that this synergistic interaction between physical and behavioral literalities may contribute to efficient scale-eating.

Gross morphology and histology of the alimentary tract of the convict cichlid Amatitlania nigrofasciata.

Science.gov (United States)

Hopperdietzel, C; Hirschberg, R M; Hünigen, H; Wolter, J; Richardson, K; Plendl, J

2014-11-01

The primary objectives of this study were to document the macroscopic and histological structure of the alimentary tract (AT) of the convict cichlid Amatitlania nigrofasciata, because there are no data available for this omnivorous freshwater fish of the family Cichlidae. The morphology of the AT of A. nigrofasciata resembles that of related species. While having morphological criteria of the AT typical of most omnivorous fishes, such as a blind sac stomach and medium length intestine, A. nigrofasciata also has some structural peculiarities: the oesophagus is lined by a uniform stratified squamous epithelial layer with interspersed goblet cells along its entire length. Additionally, it has well-developed layers of the tunica muscularis including muscle fibre bundles that ascend into its mucosal folds. Occasionally, taste buds are present. In the transitional area between oesophagus and stomach, a prominent torus-like closure device is present. The mucosa of the stomach cannot be divided into different regions according to mucosal and morphological properties. The simple pattern of intestinal loops of A. nigrofasciata has few variations, irrespective of sex, mass and length of the individual fish. The first segment of the intestine is characterized by the largest mucososerosal ratio and the most complex mucosal surface architecture. A distinction of midgut and hindgut was not possible in A. nigrofasciata due to lack of defining structural components as described for other fish species. © 2014 The Fisheries Society of the British Isles.

Human Rights and the African Renaissance | Acheampong | African ...

African Journals Online (AJOL)

This article examines the idea of African renaissance in relation to the teaching of human rights in African schools. It explores the connection between the African Renaissance and human rights, and whether there is a specific African concept of human rights. In the light of these discussions, the article sketches a perspective ...

The role of otolith size in hearing – Insights from cichlid fishes

Directory of Open Access Journals (Sweden)

Tanja Schulz-Mirbach

2015-10-01

Full Text Available Otolithic end organs in fishes function as accelerometers and are involved in the senses of balance and hearing (e.g. Popper et al. 2005. Otolith mass and shape are likely decisive factors influencing otolith motion, but while it is largely unknown how different shapes affect otolith movement relative to the sensory epithelium (Popper et al. 2005, greater otolith mass is predicted to result in enhanced stimulation of sensory hair cells and improved hearing (Lychakov and Rebane 2005. What few studies exist on this topic, however, yielded contradicting results in that they did or did not find a correlation between increased otolith mass and enhanced hearing (see Kéver et al. 2014. We investigated the relationship between otolith morphology (including 3D-models of otoliths based on high-resolution microCT imaging and otolith weight and hearing abilities in cichlids while comparing three species (Etroplus maculatus, Hemichromis guttatus, Steatocranus tinanti with different swimbladder morphology and hearing abilities (Schulz-Mirbach et al. 2014. We predicted Etroplus maculatus—the species that displays the best hearing sensitivities—to possess larger/heavier otoliths. As swimbladder extensions in this species are connected to the lagena, we further predicted to find heavier lagenar otoliths. Compared to H. guttatus and S. tinanti, E. maculatus showed the heaviest saccular otoliths, while lagenar otoliths were significantly thinner and lighter than in the former two species, apparently contradicting the hypothesis that the lagena and its otolith are primarily involved in improved hearing abilities. Our results support the idea that there is no ‘simple’ relationship between otolith weight, ancilliary auditory structures and hearing abilities. 3D-models of inner ears and otoliths may be ideally suited for future studies modeling complex otolith motion and thus, may provide a better understanding of how otolith morphology contributes to inner

The African Diaspora in continental African struggles for freedom ...

African Journals Online (AJOL)

In light of this realization, this article discusses the contributions of the African Diaspora towards continental African liberation from European colonial domination, with a view to theorizing the implications of this history on the criticism of African Renaissance literature. Focusing on Diasporan African agency in organizing ...

Evaluation of the mobile phone electromagnetic radiation on serum ...

African Journals Online (AJOL)

Evaluation of the mobile phone electromagnetic radiation on serum iron parameters in rats. ... African Health Sciences ... Background: Electromagnetic fields (EMF) created by mobile phones during communication have harmful effects on ...

Lower lethal temperatures for nonnative freshwater fishes in Everglades National Park, Florida

Science.gov (United States)

Schofield, Pam; Kline, Jeffrey L.

2018-01-01

Temperature is an important factor that shapes biogeography and species composition. In southern Florida, the tolerance of nonnative freshwater fishes to low temperatures is a critical factor in delineating their geographic spread. In this study, we provide empirical information on experimentally derived low-temperature tolerance limits of Banded Cichlid Heros severus and Spotfin Spiny Eel Macrognathus siamensis, two nonnative Everglades fishes that were lacking data, and African Jewelfish Hemichromis letourneuxi and Mayan Cichlid Cichlasoma urophthalmus, species for which previous results were derived from studies with small sample sizes. We also provide a literature review summarizing the current state of knowledge of low-temperature tolerances for all 17 nonnative freshwater fishes that have been found in Everglades National Park. Mean lower lethal temperature tolerances ranged from 4°C (Orinoco Sailfin Catfish Pterygoplichthys multiradiatus) to 16.1°C (Butterfly Peacock Bass Cichla ocellaris). These low-temperature limits may inform the understanding of the ecological role or influence of nonnative fishes and may lead to potential management opportunities and applications.

South African Association of Physicists in Medicine and Biology: 25. Anniversary Congress, 18-22 Mar 1985, Cape Town

International Nuclear Information System (INIS)

1985-01-01

The twenty-fifth anniversary congress of the South African Association of Physicists in Medicine and Biology was held from 18-22 March 1985 in Cape Town. The tremendous growth of nuclear energy and radiation technology in South Africa led to an increasing need for biophysicists, especially health physicists, for the application of radioisotopes and radiation as well as nuclear power, including the uranium industry. Papers delivered on the conference covered subjects like medical physics, radiotherapy, radiopharmaceuticals, radiation protection, the calibration of radiation monitors, radiation detectors, radiation doses and dosimetry

Male courtship preferences demonstrate discrimination against allopatric colour morphs in a cichlid fish.

Science.gov (United States)

Zoppoth, P; Koblmüller, S; Sefc, K M

2013-03-01

Whether premating isolation is achieved by male-specific, female-specific or sex-independent assortative preferences often depends on the underlying evolutionary processes. Here we test mate preferences of males presented with females of different allopatric colour variants of the cichlid fish Tropheus sp., a Lake Tanganyika endemic with rich geographical colour pattern variation, in which the strength of sexual isolation varies between populations. We conducted two-way mate choice experiments to compare behaviour of males of a red-bodied morph (population Moliro) towards females from their own population with behaviour towards females from four allopatric populations at different stages of phylogenetic and phenotypic divergence. Males courted same-population females significantly more intensely than females of other populations, and reduced their heteromorphic courtship efforts both with increasing genetic and increasing phenotypic distinctness of the females. In particular, females of a closely related red-bodied population received significantly more courtship than either genetically distinct, similarly coloured females ('Kirschfleck' morph) or genetically related, differently coloured females ('yellow-blotch' morph), both of which were courted similarly. Genetically and phenotypically distinct females (Tropheus polli) were not courted at all. Consistent with previous female-choice experiments, female courtship activity also decreased with increasing genetic distance from the males' population. Given successful experimental and natural introgression between colour morphs and the pervasive allopatry of related variants, we consider it unlikely that assortative preferences of both sexes were driven by direct selection during periods of secondary contact or, in turn, drove colour pattern differentiation in allopatry. Rather, we suggest that sexual isolation evolved as by-product of allopatric divergence. © 2012 The Authors. Journal of Evolutionary Biology © 2012

Nuclear regulation of South African mines: An industry perspective

International Nuclear Information System (INIS)

Wymer, D.G.

2001-01-01

South African mines have become subject to a rigid and prescriptive system of nuclear regulation that has its roots in the past when South Africa embarked upon a period of nuclear development spanning the full nuclear fuel cycle, and in which the South African gold mining industry once played a major part in the supply of uranium as a low grade by-product. Radiation hazards in the mines are generally very moderate, even in the few gold mines associated with uranium by-product, and to not warrant the type of regulatory attention normally applied to nuclear installations, or even to uranium mines. The continued imposition of strict nuclear regulatory requirements has caused severe financial hardship and threatens the survival of certain mining operations, while seemingly having little or no health benefits to workers or the public. With the development of modern, comprehensive mine health and safety legislation, a more appropriate, effective, and far less costly vehicle for controlling radiation hazards in mines now exists, utilizing the resources of the Mine Health and Safety Inspectorate. This approach is now being proposed, in the drafting of new legislation, as constituting a better alternative to the nuclear regulation of mines. (author)

Sociodemographic analysis of patients in radiation therapy oncology group clinical trials

International Nuclear Information System (INIS)

Chamberlain, Robert M.; Winter, Kathryn A.; Vijayakumar, Srinivasan; Porter, Arthur T.; Roach, M.; Streeter, Oscar; Cox, James D.; Bondy, Melissa L.

1998-01-01

Purpose: To assess the degree to which the sociodemographic characteristics of patients enrolled in Radiation Therapy Oncology Group (RTOG) clinical trails are representative of the general population. Methods and Materials: Sociodemographic data were collected on 4016 patients entered in 33 open RTOG studies between July 1991 and June 1994. The data analyzed included educational attainment, age, gender, and race. For comparison, we obtained similar data from the U.S. Department of Census. We also compared our RTOG data with Surveillance Epidemiology and End Results (SEER) data for patients who received radiation therapy, to determine how RTOG patients compared with cancer patients in general, and with patients with cancers at sites typically treated with radiotherapy. Results: Overall, the sociodemographic characteristics of patients entered in RTOG trials were similar to those of the Census data. We found that, in every age group of African-American men and at nearly every level of educational attainment, the proportion of RTOG trial participants mirrored the proportion in the census data. Significant differences were noted only in the youngest category of African-American men, where the RTOG accrues more in the lower educational categories and fewer with college experience. For African-American women, we found a similar pattern in every age group and at each level of educational attainment. As with men, RTOG trials accrued a considerably larger proportion of younger, less educated African-American women than the census reported. Using SEER for comparison, the RTOG enrolled proportionately more African-American men to trials all cancer sites combined, and for prostate and head and neck cancer. In head and neck trials, the RTOG enrolled nearly twice as many African-American men than would be predicted by SEER data. In lung cancer trials, RTOG underrepresented African-American men significantly; however, there was no difference for brain cancer trials. There were

Swimming with multiple propulsors: measurement and comparison of swimming gaits in three species of neotropical cichlids.

Science.gov (United States)

Feilich, Kara L

2017-11-15

Comparative studies of fish swimming have been limited by the lack of quantitative definitions of fish gaits. Traditionally, steady swimming gaits have been defined categorically by the fin or region of the body that is used as the main propulsor and named after major fish clades (e.g. carangiform, anguilliform, balistiform, labriform). This method of categorization is limited by the lack of explicit measurements, the inability to incorporate contributions of multiple propulsors and the inability to compare gaits across different categories. I propose an alternative framework for the definition and comparison of fish gaits based on the propulsive contribution of each structure (body and/or fin) being used as a propulsor relative to locomotor output, and demonstrate the effectiveness of this framework by comparing three species of neotropical cichlids with different body shapes. This approach is modular with respect to the number of propulsors considered, flexible with respect to the definition of the propulsive inputs and the locomotor output of interest, and designed explicitly to handle combinations of propulsors. Using this approach, gait can be defined as a trajectory through propulsive space, and gait transitions can be defined as discontinuities in the gait trajectory. By measuring and defining gait in this way, patterns of clustering corresponding to existing categorical definitions of gait may emerge, and gaits can be rigorously compared across categories. © 2017. Published by The Company of Biologists Ltd.

Proceedings of the Second All African IRPA Regional Radiation Protection Congress

International Nuclear Information System (INIS)

2008-01-01

The publication has been set up as proceedings of the radiation protection conference. the conference consistes of Radiation Protection Infrastructure and training; the Environmental; Occupational; Medical; Transport and Waste Safety; Emergency and Security; Non Ionizing Radiation and Miscellaneous. This conference consistes of 310p., figs., tabs., refrs

Histological review of skin cancers in African Albinos: a 10-year retrospective review

International Nuclear Information System (INIS)

Kiprono, Samson Kimaiyo; Chaula, Baraka Michael; Beltraminelli, Helmut

2014-01-01

Skin cancer is rare among Africans and albinism is an established risk for skin cancer in this population. Ultraviolet radiation is highest at the equator and African albinos living close to the equator have the highest risk of developing skin cancers. This was a retrospective study that involved histological review of all specimens with skin cancers from African albinos submitted to The Regional Dermatology Training Center in Moshi, Tanzania from 2002 to 2011. A total of 134 biopsies from 86 patients with a male to female ratio of 1:1 were reviewed. Head and neck was the commonest (n = 75, 56.0%) site affected by skin cancers. Squamous cell carcinoma (SCC) was more common than basal cell carcinoma (BCC) with a ratio of 1.2:1. Only one Acral lentiginous melanoma was reported. Majority (55.6%) of SCC were well differentiated while nodular BCC (75%) was the most common type of BCC. Squamous cell carcinoma is more common than basal cell carcinoma in African albinos

Knowledge in Radiation Protection: a Survey of Professionals in Medical Imaging, Radiation Therapy and Nuclear Medicine Units in Yaounde

International Nuclear Information System (INIS)

Ongolo-Zogo, P.; Nguehouo, M.B.; Yomi, J.; Nko'o Amven, S.

2013-01-01

Medical use of ionizing radiation is now the most common radiation source of the population at the global level. The knowledge and practices of health professionals working with X-rays determine the level and quality of implementation of internationally and nationally recommended measures for radiation protection of patients and workers. The level of implementation and enforcement of international recommendations in African countries is an issue of concern due to weak laws and regulations and regulatory bodies. We report the results of a cross-sectional survey of health professionals working with ionizing radiation in Yaounde, the capital city of Cameroon. More than 50% of these professionals have a moderate level of knowledge of the norms and principles of radiation protection and more than 80% have never attended a continuing professional development workshop on radiation protection. (authors)

Ninth national conference of the South African Section of the PRI

International Nuclear Information System (INIS)

1987-01-01

This publication contains the papers of the ninth national conference of the South African Section of the Plastics and Rubber Institute held at Johannesburg on the 22nd and 23rd October 1987. The papers cover the different applications of polymers and two seminars particularly discuss the chemical radiation effects on polymers

The African Diaspora, Civil Society and African Integration

DEFF Research Database (Denmark)

Opoku-Mensah, Paul Yaw

This paper, a work-in-progress, makes a contribution to the discussions on the appropriate modalities for incorporating the African diaspora in the African integration project.  It argues that the most appropriate entry points for incorporating the African diaspora into the integration project...... might not, necessarily, be in the formal political structures, although this is important. To the contrary, the most effective and sustainable might be within civil society---that is the links between the peoples and organizations of Africa and the diaspora. Using the case of the African academy......-- as an institution of civil society--- the paper outlines a conceptual framework for incorporating the diaspora into the African integration project....

Yolk-sac larval development of the substrate-brooding cichlid Archocentrus nigrofasciatus in relation to temperature.

Science.gov (United States)

Vlahos, Nikolaos; Vasilopoulos, Michael; Mente, Eleni; Hotos, George; Katselis, George; Vidalis, Kosmas

2015-09-01

In order to conserve and culture the cichlid fish Archocentrus nigrofasciatus, more information about its reproductive biology and its larval behavior and morphogenesis is necessary. Currently, temperatures ranging from 21 to 27 °C are used in ornamental aquaculture hatcheries. Lower temperatures are preferred to reduce the costs of water heating, and 23 °C is usually the selected temperature. However, there is limited information on culturing protocols for ornamental species and most of the information generated on this topic remains scarce. Thus, the present study examines the morphological development of Archocentrus nigrofasciatus during the yolk-sac period up to the age of 100 h post-hatching in relation to 2 temperature regimes used in ornamental aquaculture: a temperature of 27 °C (thermal optimum) and a decreased temperature of 23 °C (thermal tolerance). The results of this study suggest that the 27 °C temperature generates intense morphological changes in yolk-sac development in a shorter period. This has advantages as it reduces the time of yolk-sac larval development, and, thus, minimizes the transition phase to exogenous feeding and maximizes the efficiency at which yolk is converted into body tissues. The present paper provides necessary information to produce freshwater ornamental fish with better practices so as to increase larval survival and capitalize on time for growth. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Tolerance of nonindigenous cichlid fishes (Cichlasoma urophthalmus, Hemichromis letourneuxi) to low temperature: laboratory and field experiments in south Florida

Science.gov (United States)

Schofield, Pamela J.; Loftus, William F.; Kobza, Robert M.; Cook, Mark I.; Slone, Daniel H.

2010-01-01

The cold tolerance of two non-native cichlids (Hemichromis letourneuxi and Cichlasoma urophthalmus) that are established in south Florida was tested in the field and laboratory. In the laboratory, fishes were acclimated to two temperatures (24 and 28°C), and three salinities (0, 10, and 35 ppt). Two endpoints were identified: loss of equilibrium (11.5–13.7°C for C. urophthalmus; 10.8–12.5°C for H. letourneuxi), and death (9.5–11.1°C for C. urophthalmus; 9.1–13.3°C for H. letourneuxi). In the field, fishes were caged in several aquatic habitats during two winter cold snaps. Temperatures were lowest (4.0°C) in the shallow marsh, where no fish survived, and warmest in canals and solution-holes. Canals and ditches as shallow as 50 cm provided thermal refuges for these tropical fishes. Because of the effect on survival of different habitat types, simple predictions of ultimate geographic expansion by non-native fishes using latitude and thermal isoclines are insufficient for freshwater fishes.

Towards an indigenous African bioethics | Behrens | South African ...

African Journals Online (AJOL)

One way is for African bioethicists to begin to apply indigenous African philosophy, thought and values to ethical issues. This project is important (i) to restore dignity; (ii) because a bioethics grounded in indigenous ideas is more likely to be accepted by Africans; and (iii) because such ideas can enrich bioethical discourse.

Female genital mutilation in African and African American women's literature

Directory of Open Access Journals (Sweden)

Darja Marinšek

2007-12-01

Full Text Available The article builds on the existing dispute between African and African American women writers on the competence of writing about female genital mutilation (FGM, and tries to determine the existence and nature of the differences between the writings of these two groups. The author uses comparative analysis of two popular African and African American novels, comparing their ways of describing FGM, its causes and consequences, the level ob objectivity and the style of the narrations.This is followed by a discussion on the reasons for such differences, incorporating a larger circle of both African and African American women authors, at the same time analysing the deviance within the two groups. While the differences between African American writers are not that great, as they mostly fail to present the issue from different points of view, which is often the result of their lack of direct knowledge of the topic, African authors' writing is in itself discovered to be ambivalent and not at all invariable. The reasons for such ambivalence are then discussed in greater context, focusing on the effect of the authors' personal contact with circumcision as well as their knowledge and acceptance of Western values. The author concludes by establishing the African ambivalent attitude towards FGM, which includes different aspects of the issue, as the most significant difference between their and African American writers' description of this practice.

Evolution of Radiation Safety Culture in Africa: Impact of the Chernobyl Accident

International Nuclear Information System (INIS)

Elegba, S.

2016-01-01

The use of ionizing radiation in Africa is more than a century old but the awareness for radiation safety regulation is still a work in progress. The nuclear weapon tests carried out in the Sahara Desert during the early 1960’s and the resultant radiation fallout that drifted into West Africa with the northeasterly winds provided the first organized response to the hazards of ionizing radiation in Nigeria. The Nigerian Government in 1964 established the Federal Radiation Protection Service (FRPS) at the Physics Department of the University of Ibadan but without the force of law. In 1971, draft legislation on Nuclear Safety and Radiation Protection was submitted to Government for consideration and promulgation. It never went beyond a draft until June 1995 only after IAEA intervention! The April 1986 Chernobyl nuclear accident unfortunately did not provoke as much reaction from African countries, probably because of geography and climate: Africa is far from Ukraine and in April the winds blow from SW-NE, unlike if it had happened in December when the wind direction would have been NE-SW and Africa would have been greatly impacted with little or no radiation safety infrastructure to detect the radiation fallout or to respond to it; and weak economic infrastructure to mitigate the economic impact of such radioactive deposits on agriculture and human health. Africa was shielded by both geography and climate; but not for long. By 1988, some unscrupulous businessmen exported to Nigeria and to several African countries radiation contaminated beef and dairy products which were meant for destruction in Europe. This led to the establishment of laboratories in several African countries for the monitoring of radiation contamination of imported foods. Fortunately, the international response to the Chernobyl accident was swift and beneficial to Africa and largely spurred the establishment of radiation safety infrastructure in most if not all African Member States. Notably

Induced cytochrome P450 1A activity in cichlid fishes from Guandu River and Jacarepaguá Lake, Rio de Janeiro, Brazil.

Science.gov (United States)

Parente, Thiago E M; De-Oliveira, Ana C A X; Paumgartten, Francisco J R

2008-03-01

The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ("Nile tilapia", Oreochromis niloticus and "acará", Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepaguá Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes.

Regional and national radiation protection activities in Egypt

International Nuclear Information System (INIS)

Gomaa, M.A.M.

2008-01-01

Radiation protection activities in Egypt go back to 1957 where the Egyptian Atomic Energy Commission (EAEC) Law was issued. Radiation protection and civil defense department was one of EAEC eighth departments. Ionizing radiation law was issued in 1960 and its executive regulation in 1962. The main aim of the present work is to through some light on the current radiation protection activities in Egypt. This includes not only the role of governmental organizations but also to the non governmental organizations. Currently a new Nuclear Safety law is understudy. Regional activities such as holding the second all African IRPA regional radiation protection congress which was held in April 2007 and national training and workshops are held regularly through EAEA, AAEA and MERRCAC. (author)

Sensitivity of mesoscale modeling of smoke direct radiative effect to the emission inventory: a case study in northern sub-Saharan African region

International Nuclear Information System (INIS)

Zhang, Feng; Wang, Jun; Yang, Zhifeng; Ge, Cui; Ichoku, Charles; Hyer, Edward J; Da Silva, Arlindo; Su, Shenjian; Zhang, Xiaoyang; Kondragunta, Shobha; Kaiser, Johannes W; Wiedinmyer, Christine

2014-01-01

An ensemble approach is used to examine the sensitivity of smoke loading and smoke direct radiative effect in the atmosphere to uncertainties in smoke emission estimates. Seven different fire emission inventories are applied independently to WRF-Chem model (v3.5) with the same model configuration (excluding dust and other emission sources) over the northern sub-Saharan African (NSSA) biomass-burning region. Results for November and February 2010 are analyzed, respectively representing the start and end of the biomass burning season in the study region. For February 2010, estimates of total smoke emission vary by a factor of 12, but only differences by factors of 7 or less are found in the simulated regional (15°W–42°E, 13°S–17°N) and monthly averages of column PM 2.5 loading, surface PM 2.5 concentration, aerosol optical depth (AOD), smoke radiative forcing at the top-of-atmosphere and at the surface, and air temperature at 2 m and at 700 hPa. The smaller differences in these simulated variables may reflect the atmospheric diffusion and deposition effects to dampen the large difference in smoke emissions that are highly concentrated in areas much smaller than the regional domain of the study. Indeed, at the local scale, large differences (up to a factor of 33) persist in simulated smoke-related variables and radiative effects including semi-direct effect. Similar results are also found for November 2010, despite differences in meteorology and fire activity. Hence, biomass burning emission uncertainties have a large influence on the reliability of model simulations of atmospheric aerosol loading, transport, and radiative impacts, and this influence is largest at local and hourly-to-daily scales. Accurate quantification of smoke effects on regional climate and air quality requires further reduction of emission uncertainties, particularly for regions of high fire concentrations such as NSSA. (paper)

The Genetic Structure and History of Africans and African Americans

Science.gov (United States)

Tishkoff, Sarah A.; Reed, Floyd A.; Friedlaender, Françoise R.; Ehret, Christopher; Ranciaro, Alessia; Froment, Alain; Hirbo, Jibril B.; Awomoyi, Agnes A.; Bodo, Jean-Marie; Doumbo, Ogobara; Ibrahim, Muntaser; Juma, Abdalla T.; Kotze, Maritha J.; Lema, Godfrey; Moore, Jason H.; Mortensen, Holly; Nyambo, Thomas B.; Omar, Sabah A.; Powell, Kweli; Pretorius, Gideon S.; Smith, Michael W.; Thera, Mahamadou A.; Wambebe, Charles; Weber, James L.; Williams, Scott M.

2010-01-01

Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic properties. We observed high levels of mixed ancestry in most populations, reflecting historical migration events across the continent. Our data also provide evidence for shared ancestry among geographically diverse hunter-gatherer populations (Khoesan speakers and Pygmies). The ancestry of African Americans is predominantly from Niger-Kordofanian (~71%), European (~13%), and other African (~8%) populations, although admixture levels varied considerably among individuals. This study helps tease apart the complex evolutionary history of Africans and African Americans, aiding both anthropological and genetic epidemiologic studies. PMID:19407144

AFROSAFE Championing Radiation Safety in Africa

International Nuclear Information System (INIS)

Nyabanda, R.

2015-01-01

AFRASAFE is a campaign that was formed by Pan African congress of Radiology and imaging (PACOR) and other radiation health workers in Africa in Feb 2015. Its main objective is to unite with a common goal to identify and address issues arising from radiation protection in medicine in Africa. Through this campaign, we state that we shall promote adherence to policies, strategies and activities for the promotion of radiation safety and for maximization of benefits from radiological medical procedures. The campaign strengthens the overall radiation protection of patients, health workers and public. It promotes safe and appropriate use of ionizing radiation in medicine and enhances global information to help improve the benefit/risk dialogue with patients and the public. It enhances the safety and quality of radiological procedures in medicine, and encourages safety in diagnostic and therapeutic equipment and facilities. The issue of research in radiation protection and safety needs to be promoted. This presentation will outline the six strategic objectives and the implementation tools for radiation safety in medicine in Kenya, the challenges and way forward to achieve our goal. (Author)

The reproductive biology of an open-water spawning Lake Malawi ...

African Journals Online (AJOL)

The reproductive biology of an open-water spawning Lake Malawi cichlid, Copadichromis chrysonotus. Lance W. Smith. Abstract. Copadichromis chrysonotus is a zooplanktivorous cichlid member of the diverse fish community inhabiting Lake Malawi's rocky, littoral habitat. Like most Lake Malawi cichlids, this species' ...

Gamma radiation sterilization of Bactrocera invadens (Diptera ...

African Journals Online (AJOL)

The African invader fly, Bactrocera invadens, an invasive pest in Africa since 2003, causes damage and poses a threat to the mango and horticultural industry. Its control is therefore needed. Sterilization of males using gamma radiation doses (25, 50 and 75 Gy) as a means of population control was investigated. Irradiation ...

Occurrence of Sciadicleithrum mexicanum Kritsky, Vidal-Martinez et Rodríguez-Canul, 1994 (Monogenea: Dactylogyridae in the Cichlid Cichlasoma urophthalmus from a flooded quarry in Yucatan, Mexico

Directory of Open Access Journals (Sweden)

E. F. Mendoza-Franco

1995-06-01

Full Text Available Cichlids, Cichlasoma urophthalmus, collected in a flooded quarry in the Yucatan Peninsula, Mexico, from January through June 1992, had high levels of infection with the ancyrocephaline Sciadicleithrum mexicanum (Monogena: Dactylogyridade in all montlhly samples. Neither occurrence nor maturation of the worms eshibited any pronounced monthly fluctuation. The infection rate was found to be sizedependent, greater in longer fish. The worms occurred on primary lamellae of gill filaments of all arches, with lower numbers of parasites attached to the fourth gill arch. Otherwise, there was no significant site preference of worms. Only minor histopathological changes were found at the sites of attachment, and these were restricted to the epithelial cells of the primary lamellae of thegill filaments. The lack of seasonal periodicity in this tropical monogenean is compared to seasonal cycles typical of temperate species.

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other African academics. In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and to the rest of the world. AJOL is ... African Journal of AIDS Research.

Immunizations and African Americans

Science.gov (United States)

... Data > Minority Population Profiles > Black/African American > Immunizations Immunizations and African Americans African American adults are less ... 19 to 35 months had comparable rates of immunization. African American women are as likely to have ...

African Journals: An Evaluation of their Use in African Universities ...

African Journals Online (AJOL)

The use of African published journals in two African universities was surveyed through the use of questionnaire, interviews, journal usage count and citation analysis. The survey reveals that African published journals are not popular with academics because of lack of bibliographic and physical access. For conclusion to be ...

Ambient solar UV radiation and seasonal trends in potential sunburn ...

African Journals Online (AJOL)

Background. The detrimental effects of excess personal solar ultraviolet (UV) radiation exposure include sunburn, immunosuppression and skin cancer. In South Africa, individuals with minimum natural protection from melanin, including fair-skinned individuals and African albinos, and people spending extended ...

African Journals Online (AJOL)

African Journals Online (AJOL)

African Journals OnLine (AJOL) is the world's largest online library of ... AJOL works to change this, so that African-origin research output is available to Africans ... South African Medical Journal ... Global Journal of Pure and Applied Sciences.

Identifying tagging SNPs for African specific genetic variation from the African Diaspora Genome.

Science.gov (United States)

Johnston, Henry Richard; Hu, Yi-Juan; Gao, Jingjing; O'Connor, Timothy D; Abecasis, Gonçalo R; Wojcik, Genevieve L; Gignoux, Christopher R; Gourraud, Pierre-Antoine; Lizee, Antoine; Hansen, Mark; Genuario, Rob; Bullis, Dave; Lawley, Cindy; Kenny, Eimear E; Bustamante, Carlos; Beaty, Terri H; Mathias, Rasika A; Barnes, Kathleen C; Qin, Zhaohui S

2017-04-21

A primary goal of The Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA) is to develop an 'African Diaspora Power Chip' (ADPC), a genotyping array consisting of tagging SNPs, useful in comprehensively identifying African specific genetic variation. This array is designed based on the novel variation identified in 642 CAAPA samples of African ancestry with high coverage whole genome sequence data (~30× depth). This novel variation extends the pattern of variation catalogued in the 1000 Genomes and Exome Sequencing Projects to a spectrum of populations representing the wide range of West African genomic diversity. These individuals from CAAPA also comprise a large swath of the African Diaspora population and incorporate historical genetic diversity covering nearly the entire Atlantic coast of the Americas. Here we show the results of designing and producing such a microchip array. This novel array covers African specific variation far better than other commercially available arrays, and will enable better GWAS analyses for researchers with individuals of African descent in their study populations. A recent study cataloging variation in continental African populations suggests this type of African-specific genotyping array is both necessary and valuable for facilitating large-scale GWAS in populations of African ancestry.

Temporal variation of Mexiconema cichlasomae (Nematoda: Daniconematidae) in the Mayan cichlid fish Cichlasoma urophthalmus and its intermediate host Argulus yucatanus from a tropical coastal lagoon.

Science.gov (United States)

May-Tec, A L; Pech, D; Aguirre-Macedo, M L; Lewis, J W; Vidal-Martínez, V M

2013-03-01

The aim of the present investigation was to determine whether temporal variation in environmental factors such as rainfall or temperature influence long-term fluctuations in the prevalence and mean abundance of the nematode Mexiconema cichlasomae in the cichlid fish Cichlasoma uropthalmus and its crustacean intermediate host, Argulus yucatanus. The study was undertaken in a tropical coastal lagoon in the Yucatan Peninsula (south-eastern Mexico) over an 8-year period. Variations in temperature, rainfall and monthly infection levels for both hosts were analysed using time series and cross-correlations to detect possible recurrent patterns. Infections of M. cichlasomae in A. yucatanus showed annual peaks, while in C. urophthalmus peaks were bi-annual. The latter appear to be related to the accumulation of several generations of this nematode in C. urophthalmus. Rainfall and temperature appear to be key environmental factors in influencing temporal variation in the infection of M. cichlasomae over periods longer than a year together with the accumulation of larval stages throughout time.

Association between African American race and outcomes in patients with nonmetastatic triple-negative breast cancer: a retrospective analysis by using results from the Georgia Cancer Specialist Database.

Science.gov (United States)

Christiansen, Neal; Chen, Lei; Gilmore, James; Pechar, David; Szabo, Stephen

2012-08-01

The objective of this study was to evaluate, in a real-world context, the impact of race on disease recurrence and survival in patients with nonmetastatic triple-negative breast cancer (TNBC) treated with adjuvant chemotherapy. The study selected patients from the 2003-2008 Georgia Cancer Specialist Database with stage I-III confirmed TNBC who had received adjuvant chemotherapy. These patients were followed-up from initial diagnosis to death, cancer recurrence, or loss to follow-up. The primary outcome was disease-free survival (DFS). Kaplan-Meier curves compared DFS and recurrence between African American and non-African American groups. The impact of African American status was examined further through multivariate Cox models by adjusting for age, comorbidity, body mass index (BMI), smoking status, initial TNBC stage, surgery, and radiation therapy. Among 209 patients with TNBC, 89 (42.6%) were African American. The 2 groups (African American vs. non-African American) were similar in mean age at diagnosis (53.2 vs. 54.4 years; P =.487) and with surgery and radiation rates (98.9% vs. 100%; P = .244; 68.5% vs. 62.5%; P = .365, respectively). Compared with non-African Americans, African American patients had a higher BMI (30.4 vs. 28.6 kg/m(2); P = .0477) and were less likely to be diagnosed at stage I (31.5% vs. 51.7%; P = .0107). The African American patients had a lower 5-year DFS rate (45.2% vs. 79.7%; P = .0005) and a higher 5-year recurrence rate (42.5% vs. 7.0%; P = .0005) compared with the non-African American patients. Among patients with TNBC treated with adjuvant chemotherapy, African American race was associated with a worse outcome irrespective of later stage at presentation or higher BMI. Copyright © 2012 Elsevier Inc. All rights reserved.

Diagnosis and treatment of a dermal malignant melanoma in an African lion (Panthera leo).

Science.gov (United States)

Steeil, James C; Schumacher, Juergen; Baine, Katherine; Ramsay, Edward C; Sura, Patricia; Hodshon, Rebecca; Donnell, Robert L; Lee, Nathan D

2013-09-01

A 13-yr-old intact male African lion (Panthera leo) presented with a 4-mo history of left maxillary lip swelling. On physical examination, a 10-cm-diameter, ulcerated, round, firm, and pigmented mass at the level of the left maxillary canine tooth was noticed. All other organ systems examined were within normal limits. Multiple biopsies of the mass were collected and fixed in 10% neutral buffered formalin. Histopathologic evaluation of the biopsies revealed a malignant dermal melanoma. Hematologic and plasma biochemical parameters were within normal reference ranges. Thoracic radiographs taken 3 days following initial presentation showed no evidence of metastasis of the tumor. Computed tomography of the skull and neck was performed to evaluate local tumor invasion and to plan for hypofractionated radiation therapy. Therapy included four weekly treatments of 8 gray external-beam hypofractionated radiation and four bimonthly immunotherapy treatments. Following this treatment regime, the tumor size was reduced by 50%, and surgical excision was performed. No major side effects associated with radiation or immunotherapy were seen. Six months after diagnosis, hematologic and plasma biochemical parameters were within normal limits, thoracic radiographs showed no evidence of metastasis, and the lion showed no clinical signs of disease. The lion will continue to receive immunotherapy every 6 mo for the rest of its life. To the authors' knowledge, this is the first report of a successful treatment of a malignant dermal melanoma with external-beam hypofractionated radiation, immunotherapy, and surgical excision in an African lion.

Growth and social behavior in a cichlid fish are affected by social rearing environment and kinship

Science.gov (United States)

Hesse, Saskia; Thünken, Timo

2014-04-01

Living in groups is a widespread phenomenon in many animal taxa. The reduction of predation risk is thought to be an important cause for the formation of groups. Consequently, grouping behavior is particularly pronounced during vulnerable life stages, i.e., as juveniles. However, group living does not only provide benefits but also imposes costs on group members, e.g., increased competition for food. Thus, benefits of grouping behavior might not be evident when predation risk is absent. The adaptive significance of living and also developing in a group independent from predation risk has received relatively little attention although this might have important implications on the evolution and maintenance of group living. The first aim of the present study was to examine whether the social environment affects juvenile performance in the cichlid fish Pelvicachromis taeniatus and, secondly, whether kinship affects social behavior. Kin selection theory predicts benefits from grouping with kin. Here, we demonstrate that juveniles reared in a group grow on average faster compared to juveniles reared in isolation under standardized laboratory conditions without predation risk. Furthermore, we found significant differences in social behavior between juveniles reared in a group and reared in isolation. Fish reared in isolation were significantly more aggressive and less willing to shoal than group-reared fish. As expected, genetic relatedness influenced social behavior in group-reared fish as well: dyads of juveniles consisting of kin showed increased group cohesiveness compared to non-kin dyads. We discuss the potential benefits of group living in general and living with kin in particular.

From research to industry - the establishment of a radiation processing industry in South Africa

International Nuclear Information System (INIS)

Du Plessis, T.A.; Stevens, R.C.B.

1983-01-01

In the late sixties the South African Atomic Energy Board in pursuing its objectives to promote the peaceful application of nuclear energy in general, established a research group with the specific purpose of investigating and developing radiation processing as a new technique. During the early years it was realised that the economic and technological facets of establishing a new industry were equally important and, in addition to fundamental research, strong emphasis was placed on the necessity of marketing this new technology. Although the initial emphasis was put on gamma sterilization, and today still forms the backbone of the radiation processing industry, the promising fields of polymer modification and food irradiation hold a lot of promise in the radiation processing industry. Following ten years of successfully introducing and providing a radiation service, the South African Atomic Energy Board in 1980 decided to transfer its service to the private sector. These developments in South Africa are a good sample of how a small country, through initial government involvement, can acquire a sophisticated new private industry. (author)

Fungus-Growing Termites Originated in African Rain Forest

DEFF Research Database (Denmark)

Aanen, Duur Kornelis; Eggleton, Paul

2005-01-01

are consumed (cf. [ [1] and [2] ]). Fungus-growing termites are found throughout the Old World tropics, in rain forests and savannas, but are ecologically dominant in savannas [ 3 ]. Here, we reconstruct the ancestral habitat and geographical origin of fungus-growing termites. We used a statistical model...... of habitat switching [ 4 ] repeated over all phylogenetic trees sampled in a Bayesian analysis of molecular data [ 5 ]. Our reconstructions provide strong evidence that termite agriculture originated in African rain forest and that the main radiation leading to the extant genera occurred there. Because...

African Anthropologist

African Journals Online (AJOL)

PROMOTING ACCESS TO AFRICAN RESEARCH ... It provides a forum for African and Africanist anthropologists to publish research reports, articles, book ... A Qualitative Exploration · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

African Anthropologist: Submissions

African Journals Online (AJOL)

Author Guidelines. The African Anthropologist is a biannual journal of the Pan African Anthropological Association. It provides a forum for African and Africanist anthropologists to publish articles, research reports, review articles, and book reviews. The views expressed in any published material are those of the authors and ...

African Journals Online (AJOL)

African Journals Online (AJOL)

African Journals OnLine (AJOL) is the world's largest and pre-eminent collection of peer-reviewed, African-published scholarly journals. Historically, scholarly information has flowed from North to South and from West to East. It has also been difficult for African researchers to access the work of other African academics.

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other African academics. In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and ... Featured Country: South Africa, Featured Journal: Ergonomics SA ...

Fat, Fiber and Cancer Risk in African Americans and Rural Africans

Science.gov (United States)

O'Keefe, Stephen J.D.; Li, Jia V.; Lahti, Leo; Ou, Junhai; Carbonero, Franck; Mohammed, Khaled; Posma, Joram M; Kinross, James; Wahl, Elaine; Ruder, Elizabeth; Vipperla, Kishore; Naidoo, Vasudevan; Mtshali, Lungile; Tims, Sebastian; Puylaert, Philippe G.B.; DeLany, James; Krasinskas, Alyssa; Benefiel, Ann C.; Kaseb, Hatem O.; Newton, Keith; Nicholson, Jeremy K.; de Vos, Willem M.; Gaskins, H. Rex; Zoetendal, Erwin G.

2015-01-01

Rates of colon cancer are much higher in African Americans (65:100,000) than in rural South Africans (<5:100,000). The higher rates are associated with higher animal protein and fat and lower fiber consumption, higher colonic secondary bile acids, lower colonic short chain fatty acid quantities and higher mucosal proliferative biomarkers of cancer risk in otherwise healthy middle aged volunteers. Here we investigate further the role of fat and fiber in this association. We performed two-week food exchanges in subjects from the same populations, where African Americans were fed a high-fiber, lowfat African-style diet, and rural Africans a high-fat low-fiber western-style diet under close supervision. In comparison to their usual diets, the food changes resulted in remarkable reciprocal changes in mucosal biomarkers of cancer risk and in aspects of the microbiota and metabolome known to affect cancer risk, best illustrated by increased saccharolytic fermentation and butyrogenesis and suppressed secondary bile acid synthesis in the African Americans. PMID:25919227

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other African ... search for an article by title, author/s or keywords,; and find other information sources ... Southern African Business Review; The role played by the South African ... The Basis of Distinction Between Qualitative and Quantitative Research in ...

Trends in African philosophy

African Journals Online (AJOL)

JONATHAN

In the contention of Oladipo (2006), the debate on the idea of. African philosophy which has been divided into trends or schools, dates back to the 1960's and 70's, which constitute the modern epoch of African philosophy, when some African thinkers began to question the perspective that traditional African beliefs and.

Radiation effect of magnetohydrodynamic flow of gas between ...

African Journals Online (AJOL)

However, when the magnetic field is introduced a decrease in velocity is obtained with an increase in either radiation parameter or Reynolds number. Journal of the Nigerian Association of Mathematical Physics Vol. 10 2006: pp. 305-314. http://dx.doi.org/10.4314/jonamp.v10i1.40139 · AJOL African Journals Online.

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other African academics. In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and to the rest of the ... Egyptian Journal of Medical Human Genetics.

Genetic variation and demographic history of the Haplochromis laparogramma group of Lake Victoria-An analysis based on SINEs and mitochondrial DNA.

Science.gov (United States)

Mzighani, Semvua I; Nikaido, Masato; Takeda, Miyuki; Seehausen, Ole; Budeba, Yohana L; Ngatunga, Benjamin P; Katunzi, Egid F B; Aibara, Mitsuto; Mizoiri, Shinji; Sato, Tetsu; Tachida, Hidenori; Okada, Norihiro

2010-01-15

More than 500 endemic haplochromine cichlid species inhabit Lake Victoria. This striking species diversity is a classical example of recent explosive adaptive radiation thought to have happened within the last approximately 15,000 years. In this study, we examined the population structure and historical demography of 3 pelagic haplochromine cichlid species that resemble in morphology and have similar niche, Haplochromis (Yssichromis) laparogramma, Haplochromis (Y.) pyrrhocephalus, and Haplochromis (Y.) sp. "glaucocephalus". We investigated the sequences of the mitochondrial DNA control region and the insertion patterns of short interspersed elements (SINEs) of 759 individuals. We show that sympatric forms are genetically differentiated in 4 of 6 cases, but we also found apparent weakening of the genetic differentiation in areas with turbid water. We estimated the timings of population expansion and species divergence to coincide with the refilling of the lake at the Pleistocene/Holocene boundary. We also found that estimates can be altered significantly by the choice of the shape of the molecular clock. If we employ the nonlinear clock model of evolutionary rates in which the rates are higher towards the recent, the population expansion was dated at around the event of desiccation of the lake ca. 17,000 YBP. Thus, we succeeded in clarifying the species and population structure of closely related Lake Victoria cichlids and in showing the importance of applying appropriate clock calibrations in elucidating recent evolutionary events.

African American Diaspora

Directory of Open Access Journals (Sweden)

Angela Brown

2013-05-01

Full Text Available The migration of blacks in North America through slavery became united.  The population of blacks past downs a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape from poverty of enslavement and to establish a way of life through tradition. A way of personal freedoms was through getting a good education that lead to a better foundation and a better way of life. With regard to all historic migrations (forced and voluntary, the African Union defined the African diaspora as "[consisting] of people of African origin living outside the continent, irrespective of their citizenship and nationality and who are willing to contribute to the development of the continent and the building of the African Union." Its constitutive act declares that it shall "invite and encourage the full participation of the African diaspora as an important part of our continent, in the building of the African Union."

The Dictionary Unit for South African English. South African Concise Oxford Dictionary

Directory of Open Access Journals (Sweden)

Rajend Mesthrie

2011-10-01

Full Text Available The South African Concise Oxford Dictionary (henceforth SACOD is a South Af-rican version of the Concise Oxford Dictionary, the first time that this particular hybrid has been prepared. It is testimony to the enduring success of the work of the Dictionary Unit for South African English at Rhodes University, headed by teams that included Jean and William Branford in the 1970s, Penny Silva in the 1990s and now, Kathryn Kavanagh. The lexicographical work from the unit saw the publication of four editions of the Dictionary of Southern African English (1978, 1980, 1987, 1991, a South African Pocket Oxford Dictionary (SAPOD and the Dictionary of South African English on Historical Principles (DOSAEHP (1995. SACOD differs from the rest in several ways. It is larger in scope than SAPOD, smaller than DOSAEHP, and unlike DOSAE and DOSAEHP, does not deal with South African words alone. Based on the 10th edition of the Concise Oxford Dictionary SACOD has excised some words from the parent, whilst adding many new words of general English as well as of South Africa.

African languages and African studies librarianship: taking a ...

African Journals Online (AJOL)

Most African educational systems are centred on imported languages such as English, French, and Portuguese. The emphasis in national publishing industries on producing books, journals and newspapers overwhelmingly in those tongues is also hard to justify. It is difficult to imagine a future African renaissance that does ...

Social Realism in the African Novel: The South African and East ...

African Journals Online (AJOL)

Although the African novel arose from Europe, the African has used it to explore a different world view; a world where gods and men hold a place together in the affairs of men. But more importantly, the African novel has followed the peculiar history of colonization and decolonization. While the earlier novels depicted the ...

A survey of radiation safety training among South African ...

African Journals Online (AJOL)

Background. Ionising radiation is increasingly being used in modern medicine for diagnostic, interventional and therapeutic purposes. There has been an improvement in technology, resulting in lower doses being emitted. However, an increase in the number of procedures has led to a greater cumulative dose for patients ...

Obesity and African Americans

Science.gov (United States)

... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... youthonline . [Accessed 08/18/2017] HEALTH IMPACT OF OBESITY People who are overweight are more likely to ...

African Zoology

African Journals Online (AJOL)

African Zoology, a peer-reviewed research journal, publishes original scientific contributions and critical reviews that focus principally on African fauna in terrestrial, freshwater, and marine ecosystems. Research from other regions that advances practical and theoretical aspects of zoology will be considered. Rigorous ...

Historical colonization and dispersal limitation supplement climate and topography in shaping species richness of African lizards (Reptilia: Agaminae)

NARCIS (Netherlands)

Kissling, W.D.; Blach-Overgaard, A.; Zwaan, R.E.; Wagner, P.

2016-01-01

To what extent deep-time dispersal limitation shapes present-day biodiversity at broad spatial scales remains elusive. Here, we compiled a continental dataset on the distributions of African lizard species in the reptile subfamily Agaminae (a relatively young, Neogene radiation of agamid lizards

African Journals Online: Kenya

African Journals Online (AJOL)

Items 1 - 29 of 29 ... African Journal of Food, Agriculture, Nutrition and Development ... African and international non-governmental organizations (NGOs); African and .... for scholars and practitioners in all spheres of biological sciences to publish ...

Heart Disease and African Americans

Science.gov (United States)

... Minority Population Profiles > Black/African American > Heart Disease Heart Disease and African Americans Although African American adults are ... were 30 percent more likely to die from heart disease than non-Hispanic whites. African American women are ...

The African Political Organisation's contributions to South African ...

African Journals Online (AJOL)

The history of South African sport remains an under researched area. According to the historian, Ander Odendaal, the racist nature of 20th Century South African society implies that there are “past exclusions that persist” (Odendaal, 2006:27) In order to address this situation, a scientifichistorical enquiry into the publications ...

South African Association of Physicists in Medicine and Biology: 27. Annual congress, 11-13 Mar 1987, BLoemfontein

International Nuclear Information System (INIS)

1987-01-01

The twenty-seventh annual congress of the South African Association of Physicists in Medicine and Biology was held from 11-13 March 1987, in Bloemfontein. Papers delivered at the conference covered subjects like medical physics, radiotherapy, computed tomography, scintigraphy, radiation doses and dosimetry and radioisotopes in diagnosis

Measuring and evaluating morphological asymmetry in fish: distinct lateral dimorphism in the jaws of scale-eating cichlids.

Science.gov (United States)

Hata, Hiroki; Yasugi, Masaki; Takeuchi, Yuichi; Takahashi, Satoshi; Hori, Michio

2013-11-01

The left-right asymmetry of scale-eating Tanganyikan cichlids is described as a unilateral topographical shift of the quadratomandibular joints. This morphological laterality has a genetic basis and has therefore been used as a model for studying negative frequency-dependent selection and the resulting oscillation in frequencies of two genotypes, lefty and righty, in a population. This study aims were to confirm this laterality in Perissodus microlepis Boulenger and P. straeleni (Poll) and evaluate an appropriate method for measuring and testing the asymmetry. Left-right differences in the height of the mandible posterior ends (HMPE) and the angle between the neurocranium and vertebrae of P. microlepis and P. straeleni were measured on skeletal specimens. Snout-bending angle was also measured using a dorsal image of the same individuals following a previous method. To define which distribution model, fluctuating asymmetry (FA), directional asymmetry (DA), or antisymmetry (AS), best fit to the lateral asymmetry of the traits, we provided an R package, IASD. As a result, HMPE and neurocranium-vertebrae angle of both species were best fitted to AS, suggesting that P. microlepis and P. straeleni showed a distinct dimorphism in these traits, although snout-bending angle of P. microlepis was best fitted to FA. Measurement error was low for HMPE comparing the snout-bending angle in P. microlepis, indicating that measuring HMPE is a more accurate method. The scale-eating tribe Perissodini showed distinct antisymmetry in the jaw skeleton and neurocranium-vertebrae angle, and this laterality remains a valid marker for further evolutionary studies.

AFLP genome scans suggest divergent selection on colour patterning in allopatric colour morphs of a cichlid fish.

Science.gov (United States)

Mattersdorfer, Karin; Koblmüller, Stephan; Sefc, Kristina M

2012-07-01

Genome scan-based tests for selection are directly applicable to natural populations to study the genetic and evolutionary mechanisms behind phenotypic differentiation. We conducted AFLP genome scans in three distinct geographic colour morphs of the cichlid fish Tropheus moorii to assess whether the extant, allopatric colour pattern differentiation can be explained by drift and to identify markers mapping to genomic regions possibly involved in colour patterning. The tested morphs occupy adjacent shore sections in southern Lake Tanganyika and are separated from each other by major habitat barriers. The genome scans revealed significant genetic structure between morphs, but a very low proportion of loci fixed for alternative AFLP alleles in different morphs. This high level of polymorphism within morphs suggested that colour pattern differentiation did not result exclusively from neutral processes. Outlier detection methods identified six loci with excess differentiation in the comparison between a bluish and a yellow-blotch morph and five different outlier loci in comparisons of each of these morphs with a red morph. As population expansions and the genetic structure of Tropheus make the outlier approach prone to false-positive signals of selection, we examined the correlation between outlier locus alleles and colour phenotypes in a genetic and phenotypic cline between two morphs. Distributions of allele frequencies at one outlier locus were indeed consistent with linkage to a colour locus. Despite the challenges posed by population structure and demography, our results encourage the cautious application of genome scans to studies of divergent selection in subdivided and recently expanded populations. © 2012 Blackwell Publishing Ltd.

Retraction | Simon | African Zoology

African Journals Online (AJOL)

Panthera leo) ina. West African national park”. African Zoology is publishing an Editorial Expression of Concern regarding the following article: “New records of a threatened lion population (Panthera leo) in a West African national park” by ...

African Journals Online (AJOL)

African Journals Online (AJOL)

reviewed, African-published scholarly journals. Historically, scholarly information has flowed from North to South and from West to East. It has also been difficult for African researchers to access the work of other African academics. In partnership with ...

African Journals Online (AJOL)

African Journals Online (AJOL)

reviewed, African-published scholarly journals. Historically ... It has also been difficult for African researchers to access the work of other African academics. In partnership with ... Vol 15, No 1 (2018). SAHARA-J: Journal of Social Aspects of HIV/AIDS.

The effects of social isolation on steroid hormone levels are modulated by previous social status and context in a cichlid fish.

Science.gov (United States)

Galhardo, L; Oliveira, R F

2014-01-01

Social isolation is a major stressor which impacts the physiology, behaviour and health of individuals in gregarious species. However, depending on conditional and contextual factors, such as social status and group composition, social isolation may be perceived differently by different individuals or even by the same individuals at different times. Here we tested the effects of social status (territorial vs. non-territorial) and previous group composition (i.e. type of social group: mixed sex group with two territorial males, TT vs. mixed sex group with one territorial and one non-territorial male, TnT) on the hormonal response (androgens and cortisol) to social isolation in a cichlid fish (Oreochromis mossambicus). The different steroid hormones measured responded differentially to social isolation, and their response was modulated by social factors. Social isolation elicited a decrease of 11-keto formation only in territorial males, whereas non-territorial males present a non-significant trend for increasing KT levels. Testosterone did not respond to social isolation. Cortisol only increased in isolated individuals from TnT groups irrespective of social status (i.e. both in territorials and non-territorials). These results suggest that it is the perception of social isolation and not the objective structure of the situation that triggers the hormonal response to isolation. © 2013.

Strengthening African Union for African Integration: An African ...

African Journals Online (AJOL)

Toshiba

to secure African continent, speed up development process, and strengthen our survival ... Regional integration generally involves a somewhat complex web of cooperation ... networking of various government institutions to provide and shape.

Understanding the Rise of African Business

DEFF Research Database (Denmark)

Jorem, Kaja Tvedten; Jeppesen, Søren; Hansen, Michael W.

of African firm strategy and performance that takes into account the specificities of the African business environment and African firm capabilities. The paper starts by juxtaposing the widespread pessimistic view of African business with more recent, optimistic studies on African firms’ performance....... The latter suggests that profound improvements in African business performance are indeed under way: with the private sector playing a more important role as an engine of growth, with the rise of a capable African entrepreneurial class, and with the emergence of dynamic and competitive African enterprises...... in the literature, the authors suggest an analytical framework for understanding African business performance, underlining the interplay between contextual specificities, firm capabilities, and firm strategy....

Leadership in the African context

Directory of Open Access Journals (Sweden)

M. Masango

2002-08-01

Full Text Available The Western world has always viewed the African continent as plagued by corruption; dictatorship; military coups; rebellious leaders; greediness; misuse of power; and incompetent, politically unstable leaders - in effect, suspicious leaders who undermine their own democracies. This paper analyzes African leadership and its impact by concentrating on three historical eras, namely; the African Religious era; the Christian era, and the era of Globalization. These affected African leadership. In addition, many brilliant minds left the continent in search of greener pastures. A review of these three eras will help us understand how leadership shifted from African values into Western concepts. The role of missionaries lead African people to live with both an African and a Western concept of life. In spite of the above problems, our past leaders did their best in addressing the difficulties they faced during the three eras. African concepts of leadership were often regarded as barbaric and uncultured. Structures were evaluated by Western standards. Due to globalisation, African leaders, through programmes like NEPAD, are going back to basics, drawing on African concepts of unity among its leadership. Effectiveness or life-giving leadership is emerging and empowering villagers/communities in the continent. This type of leadership is innovative and has brought new hope for the continent.

African Journals Online (AJOL)

African Journals Online (AJOL)

African Journals OnLine (AJOL) is the world's largest and pre-eminent collection of peer-reviewed, African-published scholarly journals. Historically ... African Research Review; The Roles of Information Communication Technologies in Education: Review Article with Emphasis to the Computer and Internet Ethiopian Journal ...

African Journal on Conflict Resolution

African Journals Online (AJOL)

The African Journal on Conflict Resolution (AJCR) publishes the writings of a wide range of African and international authors in the field, but emphasis has deliberately been kept on African writers and the thinking emerging from African universities, colleges and organisations. Other websites assiciated with this Journal: ...

Globalization and African Political Science | Nnoli | African Journal ...

African Journals Online (AJOL)

No Abstract Available African Journal of Political Science Vol.8(2) 2003: 11-32. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/ajps.v8i2.27352 · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

From Contextual Theology to African Christianity: The Consideration of Adiaphora from a South African Perspective

Directory of Open Access Journals (Sweden)

Joel Mokhoathi

2017-12-01

Full Text Available The move towards contextual Christianity in Africa is an essential venture if Christianity is to communicate with the African cultural heritage. As a universal religion, Christianity has to find an expression within the cultural context. However, the contextualization of Christianity in Africa appears to have permitted the practice of syncretism. It has resulted in the emergence of African Christianity, which is the amalgamation of Christianity and African Traditional Religion. The amalgamation of Christianity and African Traditional Religion appears to overlook the essence of both religions as there is currently no clarity on how Christianity can best be expressed within the African cultural and religious heritage. This paper employs the document review method to explore the things that fall in between—“adiaphora”, which the proponents of contextual Christianity may have overlooked with regard to the African cultural and religious heritage. These include the pragmatic nature of the African cultural and religious heritage, and the African traditional methods of healing.

Infection of the muscle tissue of the filter-feeding cichlid, Chaetobranchopsis orbicularis Steindachner, 1875, by Kudoa orbicularis (Myxozoa: Multivalvulidae on Marajó Island in the Brazilian Amazon region

Directory of Open Access Journals (Sweden)

J.L. Sindeaux-Neto

Full Text Available ABSTRACT This study describes aspects of infections caused by the myxosporidian Kudoa orbicularis in filter-feeding cichlids, Chaetobranchopsis orbicularis, caught in the Arari River in the municipality of Cachoeira do Arari, on Marajó Island, Pará, Brazil. The parasite forms pseudocysts scattered throughout the striated epaxial and hypaxial muscles. Samples embedded in paraffin were analyzed histologically using hematoxylin-eosin, Gömöri, Ziehl-Neelsen, and Giemsa staining. Necropsy of the C. orbicularis specimens revealed that 100% (50/50 were infected with K. orbicularis. The specimens presented grossly abnormal muscle texture, resulting in extensive inconsistencies and weakness. Progressive softening of the muscles was observed during necropsy, indicating the rapid enzymatic autolysis of the tissue. The parasite found in the muscle tissue of C. orbicularis was identified as K. orbicularis, with clinical signs of disease being observed in the fish. The necropsy revealed extensive damage to the host organism, with well-established fibrocystic infections in the muscle fibers, associated with post mortem myoliquefaction.

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other African academics. ... search for an article by title, author/s or keywords,; and find other information ... Southern African Business Review; Project Work by Students for First ... The Basis of Distinction Between Qualitative and Quantitative Research in ...

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other African ... search for an article by title, author/s or keywords,; and find other information ... Southern African Business Review; Effect of Globalization on Sovereignty of States ... The Basis of Distinction Between Qualitative and Quantitative Research in ...

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other African ... search for an article by title, author/s or keywords,; and find other information sources ... Southern African Business Review; Conflicts in Africa: Meaning, Causes, ... The Basis of Distinction Between Qualitative and Quantitative Research in ...

How student teachers understand African philosophy

Directory of Open Access Journals (Sweden)

Matsephe M. Letseka

2012-10-01

Full Text Available The question ‘What constitutes African philosophy?’ was first raised with the publication of Placide Tempels’s seminal work Bantu philosophy in 1959. Tempels’s book inevitably elicited considerable critical response from African philosophers, which culminated in a wide range of publications such as Wiredu’s (1980 Philosophy and an African culture, Hountondji’s (1983 African philosophy: Myth and reality, Oruka’s (1990 Sage philosophy: Indigenous thinkers and modern debate on African philosophy, Shutte’s (1993 Philosophy for Africa, Masolo’s (1994 African philosophy in search of identity and Gyekye’s (1995 An essay of African philosophical thought: The Akan conceptual scheme. It has been over 60 years since the publication of Temples’s book and there continues to be serious debate about African philosophy. This article sought to contribute to the debate on the various conceptions of African philosophy, but with a focus on the challenges of teaching African philosophy to Philosophy of Education students at an open distance learning institution in South Africa. This article discussed the tendency amongst undergraduate Philosophy of Education students to conflate and reduce African philosophy to African cultures and traditions, and to the notion of ubuntu, and sought to understand the reasons for students’ inclination to treat African philosophy in this way. It examined students’ background knowledge of African philosophy, their critical thinking skills and whether their official study materials are selected and packaged in a manner that, in fact, adds to the challenges they face. Finally, the article explored the ways in which Philosophy of Education lecturers can adapt their pedagogy to provide students with a better understanding of African philosophy.

African Traditional Religion and the African Cinema: The Case of Nollywood

OpenAIRE

Akua Agyeiwaa Manieson

2014-01-01

This study aims at a discussion of the portrayal of African Traditional Religion in some selected Nollywood films. It is herein argued that Nollywood is deliberately bent on denigrating the African traditional religion. Three main religious groups are represented in Nigeria. These are Muslims forming about 50.4%, followed by Christians 48.2% while followers of other religions especially African Traditional religion, comprises 1.4% 1. This statistic has earned for Nigeria an accolade: a multi-...

African Journals Online: Health

African Journals Online (AJOL)

Items 1 - 50 of 167 ... African Journal of AIDS Research (AJAR) is a peer-reviewed ... The African Journal of Drug & Alcohol Studies is an international ... The Journal has been produced through the efforts of Kenya Medical Research Institute (KEMRI) and the African .... in basic and clinical medical sciences as well as dentistry.

African Journals Online (AJOL)

African Journals Online (AJOL)

In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and to ... African Journal of AIDS Research. Vol 35, No 2 (2017). Zimbabwe Veterinary Journal. Vol 34, No 1 (2018). Eastern Africa Social Science Research Review.

African Studies Monographs

African Journals Online (AJOL)

The African Studies Monographs is a serial that promotes research and scholarship on the African perspective worldwide. This includes matters of philosophy, history, literature, arts and culture, environment, gender, politics, administration crisis management, etc.

Alternative reproductive tactics in snail shell-brooding cichlids diverge in energy reserve allocation.

Science.gov (United States)

von Kuerthy, Corinna; Tschirren, Linda; Taborsky, Michael

2015-05-01

Life history theory predicts that the amount of resources allocated to reproduction should maximize an individual's lifetime reproductive success. So far, resource allocation in reproduction has been studied mainly in females. Intraspecific variation of endogenous energy storage and utilization patterns of males has received little attention, although these patterns may vary greatly between individuals pursuing alternative reproductive tactics (ARTs). ARTs are characterized by systematic variation of behavioral, physiological, and often morphological traits among same-sex conspecifics. Some individuals may rely on previously accumulated reserves, because of limited foraging opportunities during reproduction. Others may be able to continue foraging during reproduction, thus relying on reserves to a lesser extent. We therefore predicted that, if male tactics involve such divergent limitations and trade-offs within a species, ARTs should correspondingly differ in energy reserve allocation and utilization. To test this prediction, we studied short-term and long-term reserve storage patterns of males in the shell-brooding cichlid Lamprologus callipterus. In this species, bourgeois males investing in territory defense, courtship, and guarding of broods coexist with two distinct parasitic male tactics: (1) opportunistic sneaker males attempting to fertilize eggs by releasing sperm into the shell opening when a female is spawning; and (2) specialized dwarf males attempting to enter the shell past the spawning female to fertilize eggs from inside the shell. Sneaker males differed from other male types by showing the highest amount of accumulated short-term and long-term fat stores, apparently anticipating their upcoming adoption of the nest male status. In contrast, nest males depleted previously accumulated energy reserves with increasing nest holding period, as they invest heavily into costly reproductive behaviors while not taking up any food. This conforms to a capital

On being African and Reformed? Towards an African Reformed ...

African Journals Online (AJOL)

Here, the notions of being African and Reformed are interrogated. The research notes that these notions are rarely used in the same vein. It is admitted that notions tend to pick up different meanings as they evolve, so these notions are especially seen in that light. The theological hegemony, which in the South African ...

African Journals Online (AJOL)

African Journals Online (AJOL)

West African Journal of Applied Ecology. Vol 6, No 2 (2017). Filosofia Theoretica: Journal of African Philosophy, Culture and Religions. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL ...

Comparative support for the expensive tissue hypothesis: Big brains are correlated with smaller gut and greater parental investment in Lake Tanganyika cichlids.

Science.gov (United States)

Tsuboi, Masahito; Husby, Arild; Kotrschal, Alexander; Hayward, Alexander; Buechel, Séverine D; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas

2015-01-01

The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the energetic requirements of encephalization are suggested to impose considerable constraints on brain size evolution. Three main hypotheses concerning how energetic constraints might affect brain evolution predict covariation between brain investment and (1) investment into other costly tissues, (2) overall metabolic rate, and (3) reproductive investment. To date, these hypotheses have mainly been tested in homeothermic animals and the existing data are inconclusive. However, there are good reasons to believe that energetic limitations might play a role in large-scale patterns of brain size evolution also in ectothermic vertebrates. Here, we test these hypotheses in a group of ectothermic vertebrates, the Lake Tanganyika cichlid fishes. After controlling for the effect of shared ancestry and confounding ecological variables, we find a negative association between brain size and gut size. Furthermore, we find that the evolution of a larger brain is accompanied by increased reproductive investment into egg size and parental care. Our results indicate that the energetic costs of encephalization may be an important general factor involved in the evolution of brain size also in ectothermic vertebrates. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

A sex-specific trade-off between mating preferences for genetic compatibility and body size in a cichlid fish with mutual mate choice.

Science.gov (United States)

Thünken, Timo; Meuthen, Denis; Bakker, Theo C M; Baldauf, Sebastian A

2012-08-07

Mating preferences for genetic compatibility strictly depend on the interplay of the genotypes of potential partners and are therein fundamentally different from directional preferences for ornamental secondary sexual traits. Thus, the most compatible partner is on average not the one with most pronounced ornaments and vice versa. Hence, mating preferences may often conflict. Here, we present a solution to this problem while investigating the interplay of mating preferences for relatedness (a compatibility criterion) and large body size (an ornamental or quality trait). In previous experiments, both sexes of Pelvicachromis taeniatus, a cichlid fish with mutual mate choice, showed preferences for kin and large partners when these criteria were tested separately. In the present study, test fish were given a conflicting choice between two potential mating partners differing in relatedness as well as in body size in such a way that preferences for both criteria could not simultaneously be satisfied. We show that a sex-specific trade-off occurs between mating preferences for body size and relatedness. For females, relatedness gained greater importance than body size, whereas the opposite was true for males. We discuss the potential role of the interplay between mating preferences for relatedness and body size for the evolution of inbreeding preference.

Regulatory infrastructure for the control of radiation sources in the Africa region: Status, needs and programmes

International Nuclear Information System (INIS)

Skornik, K.

2001-01-01

In recent years, several African countries have taken steps towards creating or strengthening legal, administrative and technical mechanisms for the regulation and control of peaceful uses of nuclear technology, and towards improving the effectiveness and sustainability of radiation protection measures based on international standards. This stems from a growing awareness that a proper national infrastructure is a prerequisite for the implementation of safety standards to achieve and maintain the desired level of protection and safety, particularly in such sectors as public health and industry. Also, other issues of global and regional interest, such as the control of radiation sources, including the handling of hazardous waste, and response capabilities in the case of a radiological emergency, have contributed to a better perception of risks associated with deficiencies in or lack of adequate national radiation protection control mechanisms. Too often, however, this awareness has not been matched with adequate progress in the establishment of a regulatory framework for the control of radiation sources. This paper presents a summary of the current status of radiation protection infrastructure in all African Member States. On a background of still existing weaknesses and challenges, an overview of the Agency's response to assistance needs and programmes in this field is discussed. (author)

Pleistocene to holocene expansion of the black-belt cichlid in Central America, Vieja maculicauda (Teleostei: Cichlidae.

Directory of Open Access Journals (Sweden)

Caleb D McMahan

Full Text Available The distributions of many Northern Hemisphere organisms have been influenced by fluctuations in sea level and climatic conditions during Pleistocene interglacial periods. These cycles are associated with range contraction and refugia for northern-distributed organisms as a response to glaciers. However, lower sea levels in the tropics and sub-tropics created available habitat for expansion of the ranges of freshwater organisms. The goal of this study was to use ecological niche modeling to test the hypothesis of north to south range expansion of Vieja maculicauda associated with Pleistocene glacial cycles. Understanding the biogeography of this widespread species may help us better understand the geology and interconnectivity of Central American freshwaters. Occurrence data for V. maculicauda was based on georeferencing of all museum records of specimens recovered from FishNet2. General patterns of phylogeographic structure were assessed with mtDNA. Present day niche models were generated and subsequently projected onto paleoclimatic maps of the region during the Last Interglacial, Last Glacial Maximum, and mid-Holocene. Phylogenetic analysis of mtDNA sequence data showed no phylogeographic structure throughout the range of this widespread species. Present day niche models were congruent with the observed distribution of V. maculicauda in Central America. Results showed a lack of suitable freshwater habitat in northern Central America and Mexico during the Last Interglacial, with greatest range expansion during the Last Glacial Maximum and mid-Holocene. Results support the hypothesis of a north to south range expansion of V. maculicauda associated with glacial cycles. The wide distribution of this species compared to other closely related cichlids indicates the latter did not respond to the degree of V. maculicauda in expansion of their distributions. Future work aimed at comparisons with other species and modeling of future climatic scenarios

African Journals Online (AJOL)

African Journals Online (AJOL)

South African Journal for Research in Sport, Physical Education and Recreation. Vol 17, No 4 (2017). African Health Sciences. Vol 6, No 1 (2015). Nigeria Journal of Pure and Applied Physics. Vol 5, No 2 (2017). Journal of Student Affairs in Africa. Vol 14, No 1 (2017). Annals of African Surgery. Vol 63, No 7-9 (2018).

Population Genomics of sub-saharan Drosophila melanogaster: African diversity and non-African admixture.

Directory of Open Access Journals (Sweden)

John E Pool

Full Text Available Drosophila melanogaster has played a pivotal role in the development of modern population genetics. However, many basic questions regarding the demographic and adaptive history of this species remain unresolved. We report the genome sequencing of 139 wild-derived strains of D. melanogaster, representing 22 population samples from the sub-Saharan ancestral range of this species, along with one European population. Most genomes were sequenced above 25X depth from haploid embryos. Results indicated a pervasive influence of non-African admixture in many African populations, motivating the development and application of a novel admixture detection method. Admixture proportions varied among populations, with greater admixture in urban locations. Admixture levels also varied across the genome, with localized peaks and valleys suggestive of a non-neutral introgression process. Genomes from the same location differed starkly in ancestry, suggesting that isolation mechanisms may exist within African populations. After removing putatively admixed genomic segments, the greatest genetic diversity was observed in southern Africa (e.g. Zambia, while diversity in other populations was largely consistent with a geographic expansion from this potentially ancestral region. The European population showed different levels of diversity reduction on each chromosome arm, and some African populations displayed chromosome arm-specific diversity reductions. Inversions in the European sample were associated with strong elevations in diversity across chromosome arms. Genomic scans were conducted to identify loci that may represent targets of positive selection within an African population, between African populations, and between European and African populations. A disproportionate number of candidate selective sweep regions were located near genes with varied roles in gene regulation. Outliers for Europe-Africa F(ST were found to be enriched in genomic regions of locally

Population Genomics of Sub-Saharan Drosophila melanogaster: African Diversity and Non-African Admixture

Science.gov (United States)

Pool, John E.; Corbett-Detig, Russell B.; Sugino, Ryuichi P.; Stevens, Kristian A.; Cardeno, Charis M.; Crepeau, Marc W.; Duchen, Pablo; Emerson, J. J.; Saelao, Perot; Begun, David J.; Langley, Charles H.

2012-01-01

Drosophila melanogaster has played a pivotal role in the development of modern population genetics. However, many basic questions regarding the demographic and adaptive history of this species remain unresolved. We report the genome sequencing of 139 wild-derived strains of D. melanogaster, representing 22 population samples from the sub-Saharan ancestral range of this species, along with one European population. Most genomes were sequenced above 25X depth from haploid embryos. Results indicated a pervasive influence of non-African admixture in many African populations, motivating the development and application of a novel admixture detection method. Admixture proportions varied among populations, with greater admixture in urban locations. Admixture levels also varied across the genome, with localized peaks and valleys suggestive of a non-neutral introgression process. Genomes from the same location differed starkly in ancestry, suggesting that isolation mechanisms may exist within African populations. After removing putatively admixed genomic segments, the greatest genetic diversity was observed in southern Africa (e.g. Zambia), while diversity in other populations was largely consistent with a geographic expansion from this potentially ancestral region. The European population showed different levels of diversity reduction on each chromosome arm, and some African populations displayed chromosome arm-specific diversity reductions. Inversions in the European sample were associated with strong elevations in diversity across chromosome arms. Genomic scans were conducted to identify loci that may represent targets of positive selection within an African population, between African populations, and between European and African populations. A disproportionate number of candidate selective sweep regions were located near genes with varied roles in gene regulation. Outliers for Europe-Africa FST were found to be enriched in genomic regions of locally elevated cosmopolitan

African Journal of Marine Science

African Journals Online (AJOL)

AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... The African (formerly South African) Journal of Marine Science provides an international forum for the publication of original scientific contributions or critical reviews, ...

Leadership in the African context

OpenAIRE

M. Masango

2002-01-01

The Western world has always viewed the African continent as plagued by corruption; dictatorship; military coups; rebellious leaders; greediness; misuse of power; and incompetent, politically unstable leaders - in effect, suspicious leaders who undermine their own democracies. This paper analyzes African leadership and its impact by concentrating on three historical eras, namely; the African Religious era; the Christian era, and the era of Globalization. These affected African leadership. In ...

The African Proverbs Project and After

African Journals Online (AJOL)

rbr

links to others in Africa, Europe and America, are continuing this work on proverbs. Keywords: AFRICAN PROVERBS PROJECT, AFRICAN PROVERBS SERIES, PROVERB,. PAREMIOGRAPHY, PAREMIOLOGY. Opsomming: Die African Proverbs Project en daarna. Die Pew Charitable Trusts het die African Proverbs ...

African Philosophy and the Search for an African Philosopher: The ...

African Journals Online (AJOL)

Given Oruka, Makinde, Oladipo, Oke, and Hallen's perception of these challenges, they concede that these challenges gave birth to the postcolonial search for a distinct African identity. On the one hand, D. A. Masolo's submission that because “Africa cannot be re -subjectivised; hence, an identity which is peculiarly African ...

Attempts to sterilize Tilapia zillii by gamma irradiation for introduction into an ecosystem

International Nuclear Information System (INIS)

Andersen, A.C.; Momeni, M.H.; Nelson, S.G.; Yeo, R.R.

1975-01-01

Tilapia zillii, a cichlid fish from northern Africa, was introduced into Florida, Alabama, Arizona, and California for aquatic weed control. A study was conducted to determine if the germ cells of the fish could be selectively destroyed by ionizing radiation in doses below the lethal range in order to obviate the potential ecological problems associated with proliferation of an exotic fish species. No demonstrable effect on the gonads was shown by gamma doses up to 3300 R

Witchcraft in African and African-American Novel – A Perspective ...

African Journals Online (AJOL)

In African and therefore, African American cultural world-view, some perceive witchcraft as evil and some identify it as an art that unifies and orders ... as evil conspirators and collaborators with the demonic world who are rarely benevolent and should be purged from the society; whereas, Toni Morrison sees them as ...

African Health Sciences

African Journals Online (AJOL)

African Health Sciences is an open access, free online, internationally ... by the African Health Journals Partnership Project that is funded by the US National .... Homa Ahmadzia, Sarah Cigna, Imelda Namagembe, Charles Macri, France ... Workers (HEWs) delivering integrated community case management (iCCM) of ...

'Walk with your head high': African and African-Caribbean fatherhood, children's mental well-being and social capital.

Science.gov (United States)

Williams, Robert; Hewison, Alistair; Wagstaff, Chris; Randall, Duncan

2012-01-01

The findings presented in this article were unanticipated and came to light during a study which investigated African and African-Caribbean fathers' views about preventive primary care services. This article reports findings which indicate that African and African-Caribbean fathers strive to enable and protect children's mental well-being and create social, cultural and symbolic forms of capital. It also seeks to identify implications for health and social care policy and practice in England. There is limited literature examining African and African-Caribbean fathers' health experiences in England. Consequently an exploratory research approach was required. This involved nine, in-depth, semi-structured qualitative group interviews undertaken with 46 African and African-Caribbean fathers. The data were analysed thematically using abductive reasoning, informed by Bourdieu's theoretical work. Fathers were striving to enable and protect children's mental well-being through providing authoritative, loving, affectionate fatherhood involving reasoning, good communication and promoting self-esteem. These practices were seen to be necessary if children were to prosper in a harsh social world characterised by structural hazards including racism, negative stereotypes and limited opportunities. The fathers reported their efforts to develop what Bourdieu has termed symbolic, cultural and social capital as means of promoting the mental well-being of their children and the children of others. The implications for theory, future research, public health policy and practice, in relation to the needs of African and African-Caribbean fathers and families, are also discussed, with specific focus on how to realise the potential of African and African-Caribbean fathers' positive contributions to family and community health.

Seasonal Changes in Sleep Duration in African American and African College Students Living In Washington, D.C.

Directory of Open Access Journals (Sweden)

Janna Volkov

2007-01-01

Full Text Available Duration of nocturnal melatonin secretion, a marker of “biological night” that relates to sleep duration, is longer in winter than in summer in patients with seasonal affective disorder (SAD, but not in healthy controls. In this study of African and African American college students, we hypothesized that students who met criteria for winter SAD or subsyndromal SAD (S-SAD would report sleeping longer in winter than in summer. In addition, based on our previous observation that Africans report more “problems” with change in seasons than African Americans, we expected that the seasonal changes in sleep duration would be greater in African students than in African American students. Based on Seasonal Pattern Assessment Questionnaire (SPAQ responses, African American and African college students in Washington, D.C. (N = 575 were grouped into a winter SAD/S-SAD group or a no winter diagnosis group, and winter and summer sleep length were determined. We conducted a 2 (season × 2 (sex × 2 (ethnicity × 2 (winter diagnosis group ANCOVA on reported sleep duration, controlling for age. Contrary to our hypothesis, we found that African and African American students with winter SAD/S-SAD report sleeping longer in the summer than in the winter. No differences in seasonality of sleep were found between African and African American students. Students with winter SAD or S-SAD may need to sacrifice sleep duration in the winter, when their academic functioning/efficiency may be impaired by syndromal or subsyndromal depression, in order to meet seasonally increased academic demands.

Radiation therapy for the treatment of skin Kaposi sarcoma.

Science.gov (United States)

Tsao, May N; Sinclair, Emily; Assaad, Dalal; Fialkov, Jeff; Antonyshyn, Oleh; Barnes, Elizabeth

2016-10-01

Kaposi sarcoma (KS) lesions are purplish, reddish blue or dark brown/black macules, plaques or nodules which involve the skin and occasionally internal organs. Most patients with KS have a long indolent chronic course. A retrospective review was undertaken for all KS skin patients treated with radiotherapy at a tertiary cancer centre from Jan. 2, 1999 to Dec. 31, 2014 (inclusive). A total of 47 patients with KS (43 classical, 0 African, 1 iatrogenic, 3 AIDS related) were seen in the multidisciplinary clinic. Out of this group, 17 patients (5 females and 12 males, 14 classical, 0 African, 0 iatrogenic, 3 AIDS related) with 97 KS skin sites were treated with local external beam radiotherapy. An additional 18 skin sites were treated with repeat radiotherapy. The radiotherapy dose ranged from 6 Gy in 1 fraction to 30 Gy in 10 fractions with the most common dose fractionation scheme being 8 Gy in 1 fraction or 20 Gy in 5 daily fractions. For the previously untreated KS sites, 87% responded to radiation [30% complete response (CR) and 57% partial response (PR)]. Thirteen percent of KS sites treated with radiation progressed. For the skin sites which were treated with repeat radiotherapy, 0% showed CRs, 50% PRs and 50% had continued progression. The majority of KS skin lesions (87%) responded to radiotherapy. Patients experience minimal side effects from the palliative radiation regimens used. KS skin lesions which progress despite radiation are unlikely to show CR with repeat radiotherapy. In our experience 50% of skin KS will have partial regression with repeat radiotherapy and 50% will have continued progression.

Strengthening Radiation Protection Infrastructures in Africa: Towards Establishing Effective and Sustainable Co-operations and Networks

International Nuclear Information System (INIS)

2010-09-01

The third African IRPA 2010 conference on Strengthening Radiation Protection Infrastructures in Africa: Towards Establishing Effective and Sustainable Co-operations and Networks. IAEA's role in radiation protection with focus in Africa. The controlling of exposure to indoor Radon. And Measure of activities and calculation of effective dose of indoor 222 Rn in some dwelling and enclosed areas in Africa - capacity building for radiation protection. It had also address Patient Radiation Protection in Radiotherapy, challenges for advancing medical physic globally, Heath effects and medical applications of non-ionizing radiation, nuclear safety and radiation protection consideration in the design of research and development. The International radiation protection association (IRPA) 2010-2011 strategic plan that address among other issues educations and training activities (2000-2020) and the current UNSCLEAR activities

Solar Radiation Data Base for Nigeria | Chineke | Discovery and ...

African Journals Online (AJOL)

Solar Radiation Data Base for Nigeria. T C Chineke, J I Aina, S S Jagtap. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/dai.v11i3.15556 · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

African American Suicide

Science.gov (United States)

African American Suicide Fact Sheet Based on 2012 Data (2014) Overview • In 2012, 2,357 African Americans completed suicide in the U.S. Of these, 1,908 (80. ... rate of 9.23 per 100,000). The suicide rate for females was 1.99 per 100, ...

CONTEMPORARY AFRICAN PHILOSOPHY: EMERGENT ISSUES ...

African Journals Online (AJOL)

Dean SPGS NAU

another on meta-philosophical issues about African philosophy, their successors, in ... Key Words: African identity, hermeneutics and culture, ... Even the quest to overcome the hegemony of Western ..... African philosophers to rethink the principles, concepts, attitudes ... there is a certain openness to new possibilities at the.

African names for American plants

NARCIS (Netherlands)

Andel, van T.R.

2015-01-01

African slaves brought plant knowledge to the New World, sometimes applying it to related plants they found there and sometimes bringing Old World plants with them. By tracing the linguistic parallels between names for plants in African languages and in communities descended from African slaves,

Toward an African-Christian Demonology: The Demonologies of African Traditional Religion, African Christianity, and Early Christianity in Dialogue

Directory of Open Access Journals (Sweden)

Moscicke, Hans

2017-11-01

Full Text Available Christian interactions with the spirit-world of African traditional religion (ATR have remained problematic due, in part, to the failure of Christian missionaries to understand in detail the cosmology of ATR and the angelologies and demonologies of early Christianity. In this article I suggest a way beyond this impasse. I first survey the shape of cosmology and demonology in ATR, and then examine African Christianitys variegated responses to these traditional beliefs. Finally, I submit that a retrieval of the early Christian mythological narrative about demons and its associated cosmology could help theologians accommodate the spirit-world of ATR within a truly African-Christian theology.

A Preliminary Study on Racial Differences in HMOX1, NFE2L2, and TGFβ1 Gene Polymorphisms and Radiation-Induced Late Normal Tissue Toxicity

International Nuclear Information System (INIS)

Alam, Asim; Mukhopadhyay, Nitai D.; Ning, Yi; Reshko, Leonid B.; Cardnell, Robert J.G.; Alam, Omair; Rabender, Christopher S.; Yakovlev, Vasily A.; Walker, Linda; Anscher, Mitchell S.; Mikkelsen, Ross B.

2015-01-01

Purpose: This study tested whether racial differences in genetic polymorphisms of 4 genes involved in wound repair and response to radiation can be used to predict the occurrence of normal tissue late effects of radiation therapy and indicate potential therapeutic targets. Methods and Materials: This prospective study examined genetic polymorphisms that modulate the expression of 4 genes involved in inflammation and fibrosis and response to radiation (HMOX1, NFE2L2, NOS3, and TGFβ1). DNA from blood samples of 179 patients (∼80% breast and head and neck) collected at the time of diagnosis by their radiation oncologist as exhibiting late normal tissue toxicity was used for the analysis. Patient demographics were as follows: 56% white, 43% African American, 1% other. Allelic frequencies of the different polymorphisms of the participants were compared with those of the general American population stratified by race. Twenty-six additional patients treated with radiation, but without toxicity at 3 months or later after therapy, were also analyzed. Results: Increased frequency of a long GT repeat in the HMOX1 promoter was associated with late effects in both African American and white populations. The single nucleotide polymorphisms (SNP) rs1800469 in the TGFβ1 promoter and the rs6721961 SNP in the NFE2L2 promoter were also found to significantly associate with late effects in African Americans but not whites. A combined analysis of these polymorphisms revealed that >90% of African American patients with late effects had at least 1 of these minor alleles, and 58% had 2 or more. No statistical significance was found relating the studied NOS3 polymorphisms and normal tissue toxicity. Conclusions: These results support a strong association between wound repair and late toxicities of radiation. The presence of these genetic risk factors can vary significantly among different ethnic groups, as demonstrated for some of the SNPs. Future studies should account for the

A Preliminary Study on Racial Differences in HMOX1, NFE2L2, and TGFβ1 Gene Polymorphisms and Radiation-Induced Late Normal Tissue Toxicity

Energy Technology Data Exchange (ETDEWEB)

Alam, Asim [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Mukhopadhyay, Nitai D. [Department of Biostatistics, Virginia Commonwealth University, Richmond, Virginia (United States); Ning, Yi [Department of Family Medicine and Population Health, Virginia Commonwealth University, Richmond, Virginia (United States); Reshko, Leonid B.; Cardnell, Robert J.G.; Alam, Omair; Rabender, Christopher S.; Yakovlev, Vasily A.; Walker, Linda; Anscher, Mitchell S. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Mikkelsen, Ross B., E-mail: rmikkels@vcu.edu [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States)

2015-10-01

Purpose: This study tested whether racial differences in genetic polymorphisms of 4 genes involved in wound repair and response to radiation can be used to predict the occurrence of normal tissue late effects of radiation therapy and indicate potential therapeutic targets. Methods and Materials: This prospective study examined genetic polymorphisms that modulate the expression of 4 genes involved in inflammation and fibrosis and response to radiation (HMOX1, NFE2L2, NOS3, and TGFβ1). DNA from blood samples of 179 patients (∼80% breast and head and neck) collected at the time of diagnosis by their radiation oncologist as exhibiting late normal tissue toxicity was used for the analysis. Patient demographics were as follows: 56% white, 43% African American, 1% other. Allelic frequencies of the different polymorphisms of the participants were compared with those of the general American population stratified by race. Twenty-six additional patients treated with radiation, but without toxicity at 3 months or later after therapy, were also analyzed. Results: Increased frequency of a long GT repeat in the HMOX1 promoter was associated with late effects in both African American and white populations. The single nucleotide polymorphisms (SNP) rs1800469 in the TGFβ1 promoter and the rs6721961 SNP in the NFE2L2 promoter were also found to significantly associate with late effects in African Americans but not whites. A combined analysis of these polymorphisms revealed that >90% of African American patients with late effects had at least 1 of these minor alleles, and 58% had 2 or more. No statistical significance was found relating the studied NOS3 polymorphisms and normal tissue toxicity. Conclusions: These results support a strong association between wound repair and late toxicities of radiation. The presence of these genetic risk factors can vary significantly among different ethnic groups, as demonstrated for some of the SNPs. Future studies should account for the

Successfully Educating Our African-American Students

Science.gov (United States)

Moncree-Moffett, Kareem

2013-01-01

The purpose of this empirical study was to explore the lived experiences of African American retired female teachers who have prior experience with educating urban African American students in public schools. Also explored are the experiences of active African American female teachers of urban African American students and comparisons are…

Interventionalists’ perceptions on a culture of radiation protection

Directory of Open Access Journals (Sweden)

André Rose

2018-03-01

Full Text Available Background: Occupational exposure to ionising radiation poses potential health risks to radiation workers unless adequate protection is in place. The catheterisation laboratory is a highly contextualised workplace with a distinctive organisational and workplace culture.   Objective: This study was conducted to understand the culture of radiation protection (CRP.   Methods: This study was a qualitative study and data were collected through 30 in-depth and 6 group interviews with 54 purposively selected South African interventionalists (interventional radiologists and cardiologists. The participants included a diversity of interventionalists who varied in sex, geographic location and years of experience with fluoroscopy. The transcribed data were analysed thematically using a deductive and inductive approach.   Results: ‘Culture of radiation protection’ emerged as a complex theme that intersected with other themes: ‘knowledge and awareness of radiation’, ‘radiation safety practice’, ‘personal protective equipment (PPE utilisation’ and ‘education and training’.   Conclusion: Establishing and sustaining a CRP provides an opportunity to mitigate the potentially detrimental health effects of occupational radiation exposure. Education and training are pivotal to establishing a CRP. The time to establish a culture of radiation in the catheterisation laboratory is now.

OGIRISI: a New Journal of African Studies

African Journals Online (AJOL)

OGIRISI is a multidisciplinary journal. Its principal scope definition is focus on Africa. It therefore welcomes articles that attend to the African world, existence and development; African worldview and values; African symbols and institutions; African situation and the globalizing world; African problems and prospects. Reviews ...

Differential effects of the classroom on African American and non-African American's mathematics achievement.

Science.gov (United States)

Schenke, Katerina; Nguyen, Tutrang; Watts, Tyler W; Sarama, Julie H; Clements, Douglas H

2017-08-01

We examined whether African American students differentially responded to dimensions of the observed classroom-learning environment compared with non-African American students. Further, we examined whether these dimensions of the classroom mediated treatment effects of a preschool mathematics intervention targeted at students from low-income families. Three observed dimensions of the classroom (teacher expectations and developmental appropriateness; teacher confidence and enthusiasm; and support for mathematical discourse) were evaluated in a sample of 1,238 preschool students in 101 classrooms. Using multigroup multilevel mediation where African American students were compared to non-African American students, we found that teachers in the intervention condition had higher ratings on the observed dimensions of the classroom compared with teachers in the control condition. Further, ratings on teacher expectations and developmental appropriateness had larger associations with the achievement of African American students than for non-African Americans. Findings suggest that students within the same classroom may react differently to that learning environment and that classroom learning environments could be structured in ways that are beneficial for students who need the most support.

African Journals Online: South Africa

African Journals Online (AJOL)

Items 1 - 50 of 96 ... African Journal of Cross-Cultural Psychology and Sport Facilitation ... continent of Africa, to contribute to developing home-grown (African) methods ... Envisaged readers are academic researchers, teachers and students and practitioners in the ... that have relevance to the South African educational context.

African bees to control African elephants

Science.gov (United States)

Vollrath, Fritz; Douglas-Hamilton, Iain

2002-11-01

Numbers of elephants have declined in Africa and Asia over the past 30 years while numbers of humans have increased, both substantially. Friction between these two keystone species is reaching levels which are worryingly high from an ecological as well as a political viewpoint. Ways and means must be found to keep the two apart, at least in areas sensitive to each species' survival. The aggressive African bee might be one such method. Here we demonstrate that African bees deter elephants from damaging the vegetation and trees which house their hives. We argue that bees can be employed profitably to protect not only selected trees, but also selected areas, from elephant damage.

The physics of blackbody radiation: A review | Jain | JASSA: Journal ...

African Journals Online (AJOL)

The physics of blackbody radiation: A review. Pushpendra K Jain, Latit K Sharma. http://dx.doi.org/10.4314/jassa.v4i2.16899 · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News.

Triglyceride-based screening tests fail to recognize cardiometabolic disease in African immigrant and African-American men.

Science.gov (United States)

Yu, Sophia S K; Ramsey, Natalie L M; Castillo, Darleen C; Ricks, Madia; Sumner, Anne E

2013-02-01

The prevalence of cardiometabolic disease in Africa now rivals that of Western nations. Therefore, screening programs that lead to effective prevention of cardiometabolic disease in Africans is imperative. Most screening tests for cardiometabolic disease use triglyceride (TG) levels as a criterion. However, the failure rate of TG-based screening tests in African Americans is high. In Africans, the efficacy of TG-based screening tests is unknown. Our goal was to determine the association between hypertriglyceridemia (TG ≥150 mg/dL) and cardiometabolic disease in African and African-American men. This was a cross-sectional study of 155 men (80 African immigrants, 75 African Americans) [age, 35±9 years, mean±standard deviation (SD), body mass index (BMI) 28.5±5.2 kg/m(2)] who self-identified as healthy. Lipid profiles were performed. Glucose tolerance and insulin resistance was determined by oral glucose tolerance tests (OGTT) and the insulin sensitivity index (S(I)), respectively. Cardiometabolic disease was defined by four possible subtypes--prediabetes, diabetes, insulin resistance, or metabolic triad [hyperinsulinemia, hyperapolipoprotein B, small low-density lipoprotein (LDL) particles]. TG levels were higher in men with cardiometabolic disease than without (88±43 versus 61±26 mg/dL, Pfail to identify both African immigrants and African-American men with cardiometabolic disease. As a consequence, the opportunity for early intervention and prevention is lost.

The Dictionary Unit for South African English. South African Concise Oxford Dictionary

OpenAIRE

Rajend Mesthrie

2011-01-01

The South African Concise Oxford Dictionary (henceforth SACOD) is a South Af-rican version of the Concise Oxford Dictionary, the first time that this particular hybrid has been prepared. It is testimony to the enduring success of the work of the Dictionary Unit for South African English at Rhodes University, headed by teams that included Jean and William Branford in the 1970s, Penny Silva in the 1990s and now, Kathryn Kavanagh. The lexicographical work from the unit saw the publication of fou...

African Crop Science Journal

African Journals Online (AJOL)

AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL ... The African Crop Science Journal, a quarterly publication, publishes original ... interactions, information science, environmental science and soil science.

Diseases that turn African hair silky.

Science.gov (United States)

Ajose, Frances O A

2012-11-01

African hair in its natural state poses tenacious grooming challenges; consequently a large portion of the African cosmetic industry is focused on means to relax the tight curls of African hair to make the hair more manageable. In malnourished and hypoproteinemic states, African hair straightens in an uncomplimentary manner. Recently, we observed that in certain diseases African hair changes to a desirable silky wavy texture. To identify the diseases that turn African hair silky and their parameters we examined 5612 dermatology patients at a tertiary hospital in Nigeria. We then studied the clinical and basic laboratory parameters of those patients whose diseases were accompanied by the silky hair change. Silky hair change similar to the hair of the African neonatal child was observed in five diseases, namely AIDS, rheumatoid arthritis, systemic lupus erythematosus, pulmonary tuberculosis with cachexia, and Behçet's disease. Our study identified retrogression of African hair to the neonatal structure in five diseases. Anemia of chronic illness, high erythrocyte sedimentation rate, and mild hypocalcemia were significant laboratory parameters. This is an important observation, which should excite and advance research into the nature and structure of African hair. The causes of structural hair changes should include these five diseases. © 2012 The International Society of Dermatology.

African Journal of International Affairs

African Journals Online (AJOL)

The African Journal of International Affairs (AJIA) is a bi-annual publication of CODESRIA, Dakar, Senegal. It offers a platform for analyses on contemporary issues in African International Affairs in relation to global developments as they affect Africa. AJIA welcomes contributions in English and in French from both African ...

The Struggles over African Languages

Science.gov (United States)

Maseko, Pam; Vale, Peter

2016-01-01

In this interview, African Language expert Pam Maseko speaks of her own background and her first encounter with culture outside of her mother tongue, isiXhosa. A statistical breakdown of South African languages is provided as background. She discusses Western (originally missionary) codification of African languages and suggests that this approach…

A new cichlid fish in the Sahara: The Ounianga Serir lakes (Chad), a biodiversity hotspot in the desert.

Science.gov (United States)

Trape, Sébastien

In the rare perennial bodies of water of the Sahara desert, only a few fish species have survived to increasing aridification since the end of the last humid period at the Holocene, approximately 5000 years BP. Here, I report the occurrence of an undescribed haplochomine cichlid fish in Lake Boukou, one of the seven Ounianga Serir lakes (Chad). These lakes are located in one of the most arid areas of the Sahara desert, but they persist by virtue of subsurface inflow of fresh groundwater from a large fossil aquifer. Astatotilapia tchadensis sp. nov. is characterized by a black bar between eye and corner of mouth, rounded orange spots on anal fin, scales ctenoid, lower limb of first gill arch with 7-8 gill rackers, dorsal fin with 13-14 spines and 9-11 soft rays, anal fin with 3 spines and 8-9 soft rays, 29 or 30 lateral line scales, and lower pharyngeal dentition with enlarged molariform teeth. The new species is easily distinguished from A. desfontainii and A. flaviijosephii, the northernmost haplochromine species currently isolated from its other group members, and appears close to an unnamed species of Lake Chad basin. Ounianga Serir lakes and especially Lake Boukou present a remarkable diversity of fish, the highest known in the Sahara desert with a total of at least six fish species belonging to six genera and three families. They also constitute an exceptional natural landscape inscribed on the UNESCO world heritage list in 2012 and a biodiversity hotspot for desert vertebrate species. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Experimentally increased temperature and hypoxia affect stability of social hierarchy and metabolism of the Amazonian cichlid Apistogramma agassizii.

Science.gov (United States)

Kochhann, Daiani; Campos, Derek Felipe; Val, Adalberto Luis

2015-12-01

The primary goal of this study was to understand how changes in temperature and oxygen could influence social behaviour and aerobic metabolism of the Amazonian dwarf cichlid Apistogramma agassizii. Social hierarchies were established over a period of 96h by observing the social interactions, feeding behaviour and shelter use in groups of four males. In the experimental environment, temperature was increased to 29°C in the high-temperature treatment, and oxygen lowered to 1.0mg·L(-1)O2 in the hypoxia treatment. Fish were maintained at this condition for 96h. The control was maintained at 26°C and 6.6mg·L(-1)O2. After the experimental exposure, metabolism was measured as routine metabolic rate (RMR) and electron transport system (ETS) activity. There was a reduction in hierarchy stability at high-temperature. Aggression changed after environmental changes. Dominant and subdominant fish at high temperatures increased their biting, compared with control-dominant. In contrast, hypoxia-dominant fish decreased their aggressive acts compared with all other fish. Shelter use decreased in control and hypoxic dominant fish. Dominant fish from undisturbed environments eat more than their subordinates. There was a decrease of RMR in fish exposed to the hypoxic environment when compared with control or high-temperature fish, independent of social position. Control-dominant fish had higher RMR than their subordinates. ETS activity increased in fish exposed to high temperatures; however, there was no effect on social rank. Our study reinforces the importance of environmental changes for the maintenance of hierarchies and their characteristics and highlights that most of the changes occur in the dominant position. Copyright © 2015 Elsevier Inc. All rights reserved.

African Diaspora Associations in Denmark

DEFF Research Database (Denmark)

Vammen, Ida Marie; Trans, Lars Ove

2011-01-01

Since the early 1990s, an increasing number of African migrants have come to Denmark, where they have formed a large number of migrant associations. This chapter presents selected findings from a comprehensive survey of African diaspora associations in Denmark and focuses specifically on their tr......Since the early 1990s, an increasing number of African migrants have come to Denmark, where they have formed a large number of migrant associations. This chapter presents selected findings from a comprehensive survey of African diaspora associations in Denmark and focuses specifically...

Overview of prostate cancer in indigenous black Africans and blacks of African ancestry in diaspora 1935-2007.

Science.gov (United States)

Magoha, G A O

2007-09-01

To carry out an overview of prostate cancer in indigenous back Africans in sub-Saharan Africa and blacks of African ancestry in diaspora. Review of all published literature on prostate cancer on indigenous black Africans and Africans in diaspora was carried out through medline and index medicus searches. Published data of prostate cancer in indigenous black Africans and black men in diaspora from 1935-2007 were included in the review. Abstracts of articles identified were assessed, read and analysed to determine their possible suitability and relevance to the title under review. After establishing relevance from the abstract, the entire paper was read, and the significant points included in the review. Prostate cancer incidence and magnitude in black Africans was grossly misunderstood and underestimated in the past. Prostate cancer incidence is on the increase and currently is perhaps the most common urological malignancy affecting black Africans. Its incidence and clinical characteristics is similar to that of the Africans in diaspora but different from all other races. There currently exists significant evidence which suggests a common enhancing genetic predisposition in black men to prostate cancer. There is very urgent need for further investigation of this phenomenon through randomised controlled multicentre studies involving indigenous black Africans and black men in diaspora.

Radioactive isotopes and radiation in South Africa: a bibliographic review

International Nuclear Information System (INIS)

Basson, J.K.

1985-12-01

The development of isotope applications has been a main theme of the erstwhile Atomic Energy Board which organized a national conference in Pretoria in 1963 'to take stock of the work done in the country so far'. Radioactive isotopes and radiation have achieved widespread use in all fields of medicine, agriculture, science and technology. It was recommended that the AEC publish a review of relevant South African work. This publication therefore consists of listings of available publications by South African-based scientists since the 1963 Conference and is divided into the four categories: radiotherapy, clinical and laboratory medicine, agriculture, and industry, preceded by overviews. The terms of reference were construed not to include stable isotopes and it was accordingly decided to concentrate only on radioisotope applications

The rhetoric of Pan-Africanism and the debate on African identity in ...

African Journals Online (AJOL)

apartheid South Africa within the context of former President Mbeki's Pan-African reflections on the African Renaissance in his quest to include South Africa in two power games. Firstly, President Mbeki aims to insert South Africa into the politics of ...

The history of African trypanosomiasis

Directory of Open Access Journals (Sweden)

Steverding Dietmar

2008-02-01

Full Text Available Abstract The prehistory of African trypanosomiasis indicates that the disease may have been an important selective factor in the evolution of hominids. Ancient history and medieval history reveal that African trypanosomiasis affected the lives of people living in sub-Saharan African at all times. Modern history of African trypanosomiasis revolves around the identification of the causative agents and the mode of transmission of the infection, and the development of drugs for treatment and methods for control of the disease. From the recent history of sleeping sickness we can learn that the disease can be controlled but probably not be eradicated. Current history of human African trypanosomiasis has shown that the production of anti-sleeping sickness drugs is not always guaranteed, and therefore, new, better and cheaper drugs are urgently required.

The African agent discovered: The recognition and involvement of the African biblical interpreter in Bible translation

Directory of Open Access Journals (Sweden)

S V Coertze

2008-05-01

Full Text Available This article explores the extent to which the role of the African biblical interpreter is acknowledged in the process of Bible translation, as the Bible and Bible translation form an important part of the establishment of the African church on the continent of Africa. It points out that even though foreign discovery of African agency in Bible translation is evident, indigenous discovery of the same is largely absent. Part of the relevance of this article is for the African church to own and be actively involved in the translation of the Bible into the remaining African languages that are in need of a translation of the Bible.

South African Medical Journal

African Journals Online (AJOL)

The South African Medical Journal is published by the South African Medical Association, which represents ... G Watermeyer, S Thomson, 399-402 ... Assessing the value of Western Cape Provincial Government health administrative data and ...

Similar levels of diversity and population Structure in superflock and ...

African Journals Online (AJOL)

superflock cichlid fishes from Lake Victoria, Africa. ... Tropical Freshwater Biology ... We use DNA microsatellite loci to estimate neutral genetic diversity and the level of gene flow among populations of two cichlid species from southern Lake Victoria, ...

South African Music Studies

African Journals Online (AJOL)

SAMUS: South African Music Studies is the official organ for the South African ... Shifty Records in Apartheid South Africa: Innovations in Independent Record ... Experiences of Belonging and Exclusion in the Production and Reception of ...

African-Americans and Alzheimer's

Science.gov (United States)

... Share Plus on Google Plus African-Americans and Alzheimer's alz.org | IHaveAlz Introduction 10 Warning Signs Brain ... African-Americans are at a higher risk for Alzheimer's disease. Many Americans dismiss the warning signs of ...

Liberalism and African Culture.

Science.gov (United States)

Sindima, Harvey

1990-01-01

Discusses the effect of liberalism on the African understanding of education, community, and religion. Describes ways in which the European intrusion, that is, colonial governments, schools, and churches, undermined traditional African life and thought. (DM)

Practical radiology education in South African Dental Schools, 1981

International Nuclear Information System (INIS)

Farman, A.G.; Nortje, C.J.

1981-01-01

The current position of practical preclinical and clinical training in dento-maxillo-facial radiography for dental students and oral hygiene students in South Africa is reviewed. Special attention is given to factors in methodology which have an influence on radiation protection. Results indicate that there is a fairly high degree of standardization in dento-maxillo-facial radiography instruction in South Africa. The preference for the lead-lined or shielded open-ended cones is in keeping with the tenets of radiation protection. The use of pointed cones for intraoral radiography is not a good choice, as this causes scatter radiation. The wide use of the Rinn XCP(R) filmholding device in South African dental schools for the parallelling technique lessens the chance of cone cutting, and hence reduces the likelihood of needing to reexpose the patient due to that technical error. Additionally, the parallelling technique allows a more accurate assessment of alveolar bone loss from periodontal disease, and allows a better judgement of the relationship between the roots of maxillary teeth and the floor of the maxillary sinus, than does the bisecting angle technique. During the past decade, fiarly consistent parameters have been developed in dento-maxillo-facial radiography concerning preclinical and clinical training of dental and oral hygiene students [af

Africanization in the United States: replacement of feral European honeybees (Apis mellifera L.) by an African hybrid swarm.

Science.gov (United States)

Pinto, M Alice; Rubink, William L; Patton, John C; Coulson, Robert N; Johnston, J Spencer

2005-08-01

The expansion of Africanized honeybees from South America to the southwestern United States in feral population from the southern United States undergoing Africanization. Our microsatellite data showed that (1) the process of Africanization involved both maternal and paternal bidirectional gene flow between European and Africanized honeybees and (2) the panmitic European population was replaced by panmitic mixtures of A. m. scutellata and European genes within 5 years after Africanization. The post-Africanization gene pool (1998-2001) was composed of a diverse array of recombinant classes with a substantial European genetic contribution (mean 25-37%). Therefore, the resulting feral honeybee population of south Texas was best viewed as a hybrid swarm.

African-American Academic Nurse Leader's Role in Persistence of African-American Baccalaureate Nursing Students

Science.gov (United States)

Nelson, Kesha Marie

2017-01-01

African-American baccalaureate nursing students have a limited persistence to graduation. This constructivist grounded theory study was designed to generate a substantive theory, emerged from these data, that explained and provided insight the African-American academic nurse leader's role in the persistence to graduation of African-American…

Effects of gamma radiation on bee venom: preliminary studies

International Nuclear Information System (INIS)

Costa, H.; Boni-Mitake, M.; Souza, C.F.; Rogero, J.R.

1999-01-01

Africanized honeybees are very common insects in Brazil and frequently cause accidents followed by important immunological reactions and even deaths. Their venoms are composed of a complex mixture of substances of general biological actions. several works utilizing ionizing radiation showed that it is able to modify protein structures, and successfully detoxify snake venoms toxins, although maintaining its immunological properties. The main objective of this paper was to study the effects of gamma radiation on bee venom, regarding some biochemical and toxicological aspects. Africanized Apis melllifera whole venom (2 mg/ml) in 0.15 M Na Cl solution was irradiated with 2 kGy in a 60 Co source. Preliminary studies has been carried out in order to identify some biochemical changes after irradiation. Concerning this, irradiated and native venom were submitted to a molecular exclusion chromatography (Sephadex G-100), UV absorption spectrum and protein concentration analysis. It could be seen that irradiated bee venom spectrum presented differences when compared to native bee venom, suggesting that some structural alterations has occurred. Protein concentration and chromatography profiles were not changes after irradiation. In order to evaluate the toxicity a lethality assay (L D 50 ) has been performed with both venoms, and irradiated venom showed to be less toxic than native one. (author)

The radon daughter radiation hazard in controlled recirculation systems

International Nuclear Information System (INIS)

Rolle, R.; Burton, R.C.

1987-01-01

In deep South African gold mines, controlled recirculation systems with air cooling are being used to an increasing extent to improve the thermal environment. Recirculation causes some air to reside in the working area for a longer time than would have occurred without recirculation. Since radon daughters grow spontaneously from radon there is some concern that, with the extended residence time, the potential radiation hazard could increase to an unacceptable level. This paper describes the results obtained from a theoretical model of a controlled recirculation system. Guidelines for the design of recirculation systems to control the radon daughter radiation, and to keep it within acceptable limits are provided. 3 refs., 5 figs

African Journals Online (AJOL)

African Journals Online (AJOL)

Lwati: A Journal of Contemporary Research. Vol 14, No 3 (2017) ... Journal of Business and Administrative Studies. Vol 6, No 2 (2014) ... Vol 11 (2015): African Journal of Educational Studies in Mathematics and Sciences Vol. 11, 2015. African ...

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other ... search for an article by title, author/s or keywords,; and find other information ... Southern African Business Review; The Basis of Distinction Between Qualitative and ...

East African Medical Journal

African Journals Online (AJOL)

The East African Medical Journal is intended for publication of papers on ... research on problems relevant to East Africa and other African countries will receive special ... Analysis of survival patterns of TB‐HIV co‐infected patients in relation to ...

Predicting Non-African American Lesbian and Heterosexual Preadoptive Couples' Openness to Adopting an African American Child

Science.gov (United States)

Goldberg, Abbie E.; Smith, JuliAnna Z.

2009-01-01

Despite increases in transracial adoption, African American children remain the least likely to be adopted. No research has examined the factors that predict prospective adopters' willingness to adopt an African American child. This study used multilevel modeling to examine predictors of willingness to adopt an African American child in a sample…

Review of nuclear techniques in South African agricultural research: 1963-1984

International Nuclear Information System (INIS)

Marais, P.G.; Kotze, W.A.G.; Joubert, M.E.; Huismans, H.; Brodrick, H.T.

1985-01-01

The use of nuclear techniques in agriculture research in the RSA was reviewed at a National Conference on Nuclear Energy in 1963. Since then, 573 publications on the use of nuclear techniques in agriculture have appeared, which can be classified as follows: zoology; botany; food irradiation; soil and plant relations; soil moisture and ground water studies; and other radiation and tracer applications. A survey of literature on the use of radioactive isotopes in agriculture published between 1973 and 1980, including South African publications, was compiled by the Atomic Energy Board in 1980 but did not include any review of the scientific material

Lateralized Feeding Behavior is Associated with Asymmetrical Neuroanatomy and Lateralized Gene Expressions in the Brain in Scale-Eating Cichlid Fish

Science.gov (United States)

Lee, Hyuk Je; Schneider, Ralf F; Manousaki, Tereza; Kang, Ji Hyoun; Lein, Etienne; Franchini, Paolo

2017-01-01

Abstract Lateralized behavior (“handedness”) is unusual, but consistently found across diverse animal lineages, including humans. It is thought to reflect brain anatomical and/or functional asymmetries, but its neuro-molecular mechanisms remain largely unknown. Lake Tanganyika scale-eating cichlid fish, Perissodus microlepis show pronounced asymmetry in their jaw morphology as well as handedness in feeding behavior—biting scales preferentially only from one or the other side of their victims. This makes them an ideal model in which to investigate potential laterality in neuroanatomy and transcription in the brain in relation to behavioral handedness. After determining behavioral handedness in P. microlepis (preferred attack side), we estimated the volume of the hemispheres of brain regions and captured their gene expression profiles. Our analyses revealed that the degree of behavioral handedness is mirrored at the level of neuroanatomical asymmetry, particularly in the tectum opticum. Transcriptome analyses showed that different brain regions (tectum opticum, telencephalon, hypothalamus, and cerebellum) display distinct expression patterns, potentially reflecting their developmental interrelationships. For numerous genes in each brain region, their extent of expression differences between hemispheres was found to be correlated with the degree of behavioral lateralization. Interestingly, the tectum opticum and telencephalon showed divergent biases on the direction of up- or down-regulation of the laterality candidate genes (e.g., grm2) in the hemispheres, highlighting the connection of handedness with gene expression profiles and the different roles of these brain regions. Hence, handedness in predation behavior may be caused by asymmetric size of brain hemispheres and also by lateralized gene expressions in the brain. PMID:29069363

Neuropeptide Y in the forebrain of the adult male cichlid fish Oreochromis mossambicus: distribution, effects of castration and testosterone replacement.

Science.gov (United States)

Sakharkar, Amul J; Singru, Praful S; Sarkar, Koustav; Subhedar, Nishikant K

2005-08-22

We studied the organization of the neuropeptide Y (NPY)-immunoreactive system in the forebrain of adult male cichlid fish Oreochromis mossambicus and its response to castration and testosterone replacement by using morphometric methods. Immunoreactivity for NPY was widely distributed in the forebrain, and the pattern generally resembled that in other teleosts. Whereas immunoreactivity was conspicuous in the ganglia of nervus terminalis (NT; or nucleus olfactoretinalis), a weak reaction was detected in some granule cells in the olfactory bulb and in the cells of area ventralis telencephali pars lateralis (Vl). Moderately to intensely immunoreactive cells were distinctly seen in the nucleus entopeduncularis (NE), nucleus preopticus (NPO), nucleus lateralis tuberis (NLT), paraventricular organ (PVO), and midbrain tegmentum (MT). NPY fibers were widely distributed in the forebrain. Castration for 10/15 days resulted in a drastic loss of immunoreactivity in the cells of NE (P<0.001) and a significant decrease (P<0.01) in their cell nuclear size. However, cell nuclei of the NT neurons showed a significant increase in size. A highly significant reduction in the NPY-immunoreactive fiber density (P<0.001) was observed in several areas of the forebrain. Although testosterone replacement reversed these changes, fibers in some areas showed supranormal responses. Immunoreactive cells in Vl, NPO, NLT, PVO, and MT and fiber density in some other areas did not respond to castration. We suggest that the NPY-immunoreactive elements that respond to castration and testosterone replacement may serve as the substrate for processing the positive feedback action of the steroid hormone. (c) 2005 Wiley-Liss, Inc.

African Journals Online (AJOL)

African Journals Online (AJOL)

Continuing Medical Education; The competitive advantage of nations: is Porter's Diamond Framework a new theory that explains the international competitiveness of ... African Journal of Biotechnology; The application of just administrative action in the South African environmental governance sphere: An analysis of some ...

African Journals Online (AJOL)

African Journals Online (AJOL)

African Journals OnLine (AJOL) is the world's largest and pre-eminent collection of peer-reviewed, African-published scholarly journals. Historically, scholarly information ... Ethiopian Journal of Education and Sciences; Advertising practice in Nigeria: Development, new trends, challenges and prospects. EJOTMAS: Ekpoma ...

African Journals Online (AJOL)

African Journals Online (AJOL)

African Journals OnLine (AJOL) is the world's largest and pre-eminent collection of peer-reviewed, African-published scholarly journals. ... Continuing Medical Education; The competitive advantage of nations: is Porter's Diamond Framework a new theory that explains the international competitiveness of countries?

African Journals Online (AJOL)

African Journals Online (AJOL)

African Journals OnLine (AJOL) is the world's largest and pre-eminent collection of peer-reviewed, African-published scholarly journals. Historically, scholarly information has flowed ... Thought and Practice; Advertising practice in Nigeria: Development, new trends, challenges and prospects. EJOTMAS: Ekpoma Journal of ...

African Journals Online: African Studies

African Journals Online (AJOL)

Items 1 - 50 of 56 ... Africa Development is the quarterly bilingual journal of CODESRIA. .... relationship in the family, workplace, schools and organisations. .... activities, and personalities driving the democracy and development agenda in the region; 4. Conflict .... with preference for the results of African and Africanist studies.

Redescription of Neoechinorhynchus (Neoechinorhynchus) golvani Salgado-Maldonado, 1978 (Acanthocephala: Neoechinorhynchidae) and description of a new species from freshwater cichlids (Teleostei: Cichlidae) in Mexico.

Science.gov (United States)

Salgado-Maldonado, Guillermo

2013-05-01

A redescription of Neoechinorhynchus (Neoechinorhynchus) golvani Salgado-Maldonado (An Inst Biol Univ Nal Autón Méx, Ser Zool 49:35-47, 1978) is presented, based on adult specimens collected from the type host Paraneetroplus fenestratus from the type location, the Lago de Catemaco lake, Veracruz state, Mexico, and its presence is recorded in other cichlids. Detailed studies of N. (N.) golvani using light microscopy revealed some taxonomically important, previously unreported features, such as the size and shape of fully developed adult males and females, and the structure of the eggs. Morphological variability in N. (N.) golvani is described. Based on these data, the geographic distribution of this species is documented. Neoechinorhynchus (Neoechinorhynchus) panucensis n. sp. is described from Herichthys labridens (Pellegrin), Amatitlania nigrofasciata (Günther), and Herichthys cyanoguttatus Baird and Girard (all of them Cichlidae), collected in the Río Atlapexco, a tributary to the upper Río Panuco basin, Hidalgo State, Mexico. This new species stand up alone because of its minute proboscis (♂ 50 × 60, ♀ 42-55 (48.5) × 48-63 (57.7)) and anterior hooks (♂ 27-30 (28.8) × 3-5 (4), ♀ 28-32 (30) × 5 (5)). A key to the species of Neoechinorhynchus recorded from freshwater fishes in Central and South America is included.

Dietary Fat and Vitamin E in Prostate Cancer Risk Among African Americans and Africans: A Case-Control Study

National Research Council Canada - National Science Library

Ukoli, Flora A; Smith, Ernest; Malin, Alecia; Zhao, Barbara; Osime, Usifo; Stain, Steven

2006-01-01

The role of dietary fat and vitamin E in prostate cancer risk among African-Americans, African migrants and Africans is being investigated using a dietary assessment tool and by measuring plasma fatty...

African Journals Online (AJOL)

African Journals Online (AJOL)

Ethiopian Journal of Education and Sciences; Conflicts in Africa: Meaning, Causes, Impact and Solution African Research Review; The competitive advantage of nations: is Porter's Diamond Framework a new theory that explains the international competitiveness of countries? Southern African Business Review; The Rise of ...

African Journals Online (AJOL)

African Journals Online (AJOL)

Mizan Law Review; The competitive advantage of nations: is Porter's Diamond Framework a new theory that explains the international competitiveness of countries? ... African Journal of Biotechnology; The application of just administrative action in the South African environmental governance sphere: An analysis of some ...

Mechanisms of Vowel Variation in African American English.

Science.gov (United States)

Holt, Yolanda Feimster

2018-02-15

This research explored mechanisms of vowel variation in African American English by comparing 2 geographically distant groups of African American and White American English speakers for participation in the African American Shift and the Southern Vowel Shift. Thirty-two male (African American: n = 16, White American controls: n = 16) lifelong residents of cities in eastern and western North Carolina produced heed,hid,heyd,head,had,hod,hawed,whod,hood,hoed,hide,howed,hoyd, and heard 3 times each in random order. Formant frequency, duration, and acoustic analyses were completed for the vowels /i, ɪ, e, ɛ, æ, ɑ, ɔ, u, ʊ, o, aɪ, aʊ, oɪ, ɝ/ produced in the listed words. African American English speakers show vowel variation. In the west, the African American English speakers are participating in the Southern Vowel Shift and hod fronting of the African American Shift. In the east, neither the African American English speakers nor their White peers are participating in the Southern Vowel Shift. The African American English speakers show limited participation in the African American Shift. The results provide evidence of regional and socio-ethnic variation in African American English in North Carolina.

The ethics of improving African traditional medical practice: scientific or African traditional research methods?

Science.gov (United States)

Nyika, Aceme

2009-11-01

The disease burden in Africa, which is relatively very large compared with developed countries, has been attributed to various factors that include poverty, food shortages, inadequate access to health care and unaffordability of Western medicines to the majority of African populations. Although for 'old diseases' knowledge about the right African traditional medicines to treat or cure the diseases has been passed from generation to generation, knowledge about traditional medicines to treat newly emerging diseases has to be generated in one way or another. In addition, the existing traditional medicines have to be continuously improved, which is also the case with Western scientific medicines. Whereas one school of thought supports the idea of improving medicines, be they traditional or Western, through scientific research, an opposing school of thought argues that subjecting African traditional medicines to scientific research would be tantamount to some form of colonization and imperialism. This paper argues that continuing to use African traditional medicines for old and new diseases without making concerted efforts to improve their efficacy and safety is unethical since the disease burden affecting Africa may continue to rise in spite of the availability and accessibility of the traditional medicines. Most importantly, the paper commends efforts being made in some African countries to improve African traditional medicine through a combination of different mechanisms that include the controversial approach of scientific research on traditional medicines.

African Retentions in Blues and Jazz.

Science.gov (United States)

Meadows, Eddie S.

1979-01-01

The perseverance of African musical characteristics among American Blacks is an historic reality. African retentions have been recorded in Black music of the antebellum period. Various African scales and rhythms permeate Black American music today as evidenced in the retentions found in blues and jazz. (RLV)

On Delimiting African Philosophy and the Equalization Scheme ...

African Journals Online (AJOL)

One of these dimensions is African Philosophy where lots of African scholars have invested their time and mind on examining the African universe and bringing forth various descriptions of the African life. And in line with this, some schools of thought in African Philosophy have developed. It seems to me that these schools ...

"Women...mourn and men carry on": African women storying mourning practices: a South African example.

Science.gov (United States)

Kotzé, Elmarie; Els, Lishje; Rajuili-Masilo, Ntsiki

2012-09-01

African mourning of loss of lives in South Africa has been shaped by discursive practices of both traditional African cultures and the sociopolitical developments under apartheid and in post-apartheid South Africa. This article reports on changes in mourning practices on the basis of a literature review and uses a collection of examples to highlight the navigation of some cultural and gendered issues relating to mourning, against the backdrop of the everyday experiences of loss of life in South Africa due to violence and HIV/AIDS. The article draws on African womanist and feminist scholarship and focuses on the intersections between cultural and gender practices of bereavement in the lives of professional urban African women. The authors argue for the use of positioning theory and witnessing practices to honor and story the ongoing struggle of African women as these women take different agentic positions by accepting, questioning, resisting, and/or changing cultural mourning practices while they compassionately witness the self and others in the narratives they live.

African Peacekeepers in Africa

DEFF Research Database (Denmark)

Emmanuel, Nikolas G.

2015-01-01

behind African participation in United Nations (UN) peacekeeping operations in Africa. In doing so, this research focuses on US military aid and foreign troop training from 2002 to 2012, and its impact on African deployments into UN peacekeeping missions in Africa. As can be expected, such third...

African Journals Online (AJOL)

African Journals Online (AJOL)

African Journal of Oral Health. Vol 35, No 1-2 (2017). Egyptian Journal of Biochemistry and Molecular Biology. Vol 7, No 3 (2017). African Journal of Chemical Education. Vol 8, No 2 (2017): Journal of Language, Technology & Entrepreneurship in Africa. Journal of Language, Technology & Entrepreneurship in Africa.

African Journals Online: Uganda

African Journals Online (AJOL)

Items 1 - 12 of 12 ... The African Crop Science Journal, a quarterly publication, publishes original ... by the African Health Journals Partnership Project that is funded by the US .... the role, development, management and improvement of higher education from an ... France, France, MEtropolitan, French Guiana, French Polynesia ...

Toward an African-Christian Demonology: The Demonologies of African Traditional Religion, African Christianity, and Early Christianity in Dialogue

OpenAIRE

Moscicke, Hans

2017-01-01

Christian interactions with the spirit-world of African traditional religion (ATR) have remained problematic due, in part, to the failure of Christian missionaries to understand in detail the cosmology of ATR and the angelologies and demonologies of early Christianity. In this article I suggest a way beyond this impasse. I first survey the shape of cosmology and demonology in ATR, and then examine African Christianitys variegated responses to these traditional beliefs. Finally, I submit that ...

AFRICAN SOLUTIONS TO AFRICA'S PROBLEMS? AFRICAN ...

African Journals Online (AJOL)

Ilse van der Walt

characterised by a volatile mix of conflict, instability and state weakness, and analysts ... to ensure peace, security and stability on the continent at national, ... half a dozen African economies have been growing at more than 6 per cent per year.

The emergence and trajectories of struggles for an 'African university': The case of unfinished business of African epistemic decolonisation

Directory of Open Access Journals (Sweden)

Sabelo J. Ndlovu-Gatsheni

Full Text Available The decolonial departure point of this article is that every human being is born into a valid and legitimate knowledge system. This means that African people had their own valid and legitimate indigenous systems of education prior to colonisation. However, the dawn and unfolding of Eurocentric modernity through colonialism and imperialism unleashed a particularly racial ethnocentric attitude that led European colonialists to question the very humanity of African people. This questioning and sometimes outright denial of African people's humanity inevitably enabled not only genocides but epistemicides, linguicides and cultural imperialism. The long-term consequence was that Western education became propagated as the only valid and legitimate form of socialisation of humanity across space and time. Needless to say, indigenous African systems of education were displaced as the idea of the modern university took root in Africa. This article flashes back to precolonial African/Nilotic/Arab/Muslim intellectual traditions in its historical reflection on the idea of the university in Africa. It posits a 'triple heritage' of higher education, which embraces Western imperial/ colonial modernity and anti-colonial nationalist liberatory developmentalism in its engagement with the contested idea of the university in Africa. The article critically examines the long and ongoing African struggles for an 'African university'. It locates the struggles for an African university within the broader context of African liberation struggles, the search for modern African identity, autonomous African development and self-definition. Four core challenges constitutive of the struggle for an African university are highlighted: the imperative of securing Africa as a legitimate epistemic base from which Africans view and understand the world; the task of'moving the centre' through shifting the geography and biography of knowledge in a context where what appears as 'global

African Journals Online (AJOL)

African Journals Online (AJOL)

Historically, scholarly information has flowed from North to South and from West to East. It has also been difficult for African researchers to access the work of other African academics. In partnership with hundreds of journals from all ... Featured Country: Nigeria, Featured Journal: Nigeria Journal of Business Administration ...

Inspired by African Art.

Science.gov (United States)

Heintz, June Rutledge

1991-01-01

Argues that African art helps children to learn vital art concepts and enlarges their understanding of the role of art in human culture. Outlines a unit on African art based on animals. Students created fabric designs and illustrated folktales and fables. Provides a list of free resources. (KM)

Panafricanism, African Boundaries and Regional Integration ...

African Journals Online (AJOL)

The Pan African idea of closer unity is examined. Regional economic integration as a Pan African perspective is presented as a major way out of the deep and worsening economic crises bedeviling African economics. Attempts have been made since the 1960s to create and re-create institutions for regional economic ...

Structural Analysis of Insulin Minisatellite Alleles Reveals Unusually Large Differences in Diversity between Africans and Non-Africans

Science.gov (United States)

Stead, John D. H.; Jeffreys, Alec J.

2002-01-01

The insulin minisatellite (INS VNTR) associates with susceptibility to a variety of diseases. We have developed a high-resolution system for analyzing variant repeat distributions applicable to all known minisatellite alleles, irrespective of size, which allows lineages of related alleles to be identified. This system has previously revealed extremely low structural diversity in the minisatellite among northern Europeans from the United Kingdom, with all alleles belonging to one of only three highly diverged lineages called “I,” “IIIA,” and “IIIB.” To explore the origins of this remarkably limited lineage diversity, we have characterized an additional 780 alleles from three non-African and three African populations. In total, 22 highly diverged lineages were identified, with structural intermediates absent from extant populations, suggesting a bottleneck within the ancestry of all humans. The difference between levels of diversity in Africans and non-Africans is unusually large, with all 22 lineages identified in Africa compared with only three lineages seen not only in the United Kingdom but also in the other non-African populations. We also find evidence for overrepresentation of lineage I chromosomes in non-Africans. These data are consistent with a common out-of-Africa origin and an unusually tight bottleneck within the ancestry of all non-African populations, possibly combined with differential and positive selection for lineage I alleles in non-Africans. The important implications of these data for future disease-association studies are discussed. PMID:12404181

African Journals Online (AJOL)

African Journals Online (AJOL)

In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and to the rest of the world. ... AFRREV IJAH: An International Journal of Arts and Humanities; Human Rights under the Ethiopian Constitution: A Descriptive Overview

African Journals Online (AJOL)

African Journals Online (AJOL)

It has also been difficult for African researchers to access the work of other ... search for an article by title, author/s or keywords,; and find other information ... Southern African Business Review; Income Tax Assignment under the ... Mizan Law Review; The Basis of Distinction Between Qualitative and Quantitative Research in ...

Keeping African Masks Real

Science.gov (United States)

Waddington, Susan

2012-01-01

Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

Understanding the Rise of African Business

DEFF Research Database (Denmark)

Jorem, Kaja Tvedten; Hansen, Michael Wendelboe; Jeppesen, Søren

2014-01-01

Purpose: In light of recent enthusiasm over African private sector development, the purpose of this paper is to review the business literature on African enterprise development with a view of identifying lacunas in the literature and of developing an analytical framework that may guide future...... research on this issue. Design/methodology/approach: The paper provides a review of the extant literature on African enterprise development by juxtaposing the traditional pessimistic view of African business performance with more recent, optimistic accounts. Based on the literature review, lacunas...... enterprises, observing that while much research is focusing on the role of the African business environments for enterprise development, much less attention has been devoted to the role of firm-specific capabilities, strategies and management. The paper concludes by advocating a contingency approach...

Cytomegalovirus Infections among African-Americans

Directory of Open Access Journals (Sweden)

Best Al M

2008-08-01

Full Text Available Abstract Background Since African-Americans have twice the prevalence of cytomegalovirus (CMV infections as age-matched Caucasians we sought to determine the ages and possible sources of infection of African-American children. Methods Subjects were 157 African-American healthy children and adolescents and their 113 household adults in Richmond VA. Families completed a questionnaire, provided saliva for antibody testing, and adolescents were interviewed regarding sexual activity. Results Regardless of age CMV seropositivity was not associated with gender, breast feeding, health insurance, sexual activity, or household income, education, or size. In the final regression model, prior CMV infection in adults was over two-fold higher than in children (chi-square = 18.8, p Conclusion We observed that African-American children had CMV seroprevalence rates by age 20 years at less than one-half of that of their adult mothers and caregivers. Sibling-to-sibling transmission was a likely source of CMV infections for the children. The next generation of African-American women may be highly susceptible to a primary CMV infection during pregnancy and may benefit from a CMV vaccine.

Impediments to the successful reconstruction of African immigrant teachers' professional identities in South African schools

Directory of Open Access Journals (Sweden)

Saloshna Vandeyar

2014-06-01

Full Text Available The purpose of this study was to explore difficulties and challenges that confront African immigrant teachers as they attempt to reconstruct their professional identities in South African schools. The study was qualitative in nature and utilized narrative inquiry and the case study approach. Data-gathering techniques included a mix of semi-structured interviews, observations, focus group interviews, field notes and researcher journals. Data were analysed using grounded theory and content analysis methods. Findings of the study revealed that immigration status, employment status, attitudes of indigenous learners and holding on to former culture or way of knowing due to lack of induction or mentoring, were impediments to the successful reconstruction of African immigrant teachers' professional identities in South African schools.

Worse Cardiometabolic Health in African Immigrant Men than African American Men: Reconsideration of the Healthy Immigrant Effect

OpenAIRE

O'Connor, Michelle Y.; Thoreson, Caroline K.; Ricks, Madia; Courville, Amber B.; Thomas, Francine; Yao, Jianhua; Katzmarzyk, Peter T.; Sumner, Anne E.

2014-01-01

Background: The healthy immigrant effect is a phrase that has been used for decades to describe better cardiometabolic health in African immigrants than African Americans. The recent global increase in cardiometabolic diseases raises the possibility that immigrant health may be changing. Therefore, a new assessment of cardiometabolic health in African immigrants is warranted.

South African Journal of Education

African Journals Online (AJOL)

The South African Journal of Education (SAJE) publishes original research articles reporting on research ... professional scientist and which critically evaluate the research done in a specific field in education; ... AJOL African Journals Online.

Dietary Fat and Vitamin E in Prostate Cancer Risk Among African Americans and West Africans: A Case-Control Study

National Research Council Canada - National Science Library

Ukoli, Flora A; Smith, Ernest; Malin, Alecia; Zhao, Barbara; Osime, Usifo; Stain, Steven

2005-01-01

The role of dietary fat and vitamin E in prostate cancer risk among African-Americans, African migrants and Africans is being investigated using a dietary assessment tool and by measuring plasma fatty...

African Journals Online: Guernsey

African Journals Online (AJOL)

African Journals Online: Guernsey. Home > African Journals Online: Guernsey. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online: Grenada

African Journals Online (AJOL)

African Journals Online: Grenada. Home > African Journals Online: Grenada. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online: India

African Journals Online (AJOL)

African Journals Online: India. Home > African Journals Online: India. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access. Afghanistan ...

African Journals Online: Barbados

African Journals Online (AJOL)

African Journals Online: Barbados. Home > African Journals Online: Barbados. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online: Malta

African Journals Online (AJOL)

African Journals Online: Malta. Home > African Journals Online: Malta. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access. Afghanistan ...

African Journals Online: Bahamas

African Journals Online (AJOL)

African Journals Online: Bahamas. Home > African Journals Online: Bahamas. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online: Liechtenstein

African Journals Online (AJOL)

African Journals Online: Liechtenstein. Home > African Journals Online: Liechtenstein. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online: Vanuatu

African Journals Online (AJOL)

African Journals Online: Vanuatu. Home > African Journals Online: Vanuatu. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

Annals of African Surgery

African Journals Online (AJOL)

The goal of the Annals of African Surgery is to provide a medium for the exchange of current information between surgeons in the African region. The journal embraces surgery in all its aspects; basic science, clinical research, experimental research, surgical education. It will assist surgeons in the region to keep abreast of ...

African Journals Online (AJOL)

African Journals Online (AJOL)

In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and to the rest of the world. AJOL is a Non-Profit Organisation ... Featured Country: Nigeria, Featured Journal: Journal of Applied Science, Engineering and Technology ...

African Journals Online: Aruba

African Journals Online (AJOL)

African Journals Online: Aruba. Home > African Journals Online: Aruba. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access. Afghanistan ...

African Journals Online: Kazakhstan

African Journals Online (AJOL)

African Journals Online: Kazakhstan. Home > African Journals Online: Kazakhstan. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

South African Family Practice

African Journals Online (AJOL)

South African Family Practice(SAFP) is a peer-reviewed scientific journal, which strives to ... The content of SAFP is designed to reflect and support further development of the broad ... Vol 60, No 2 (2018) ... of doctors and physiotherapists in the rehabilitation of people living with HIV · EMAIL ... AJOL African Journals Online.

Annals of African Medicine

African Journals Online (AJOL)

The Annals of African Medicine is published by the Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria and the Annals of African Medicine Society. The Journal is intended to serve as a medium for the publication of research findings in the broad field of Medicine in Africa and other developing countries, and ...

African Journals Online: Andorra

African Journals Online (AJOL)

African Journals Online: Andorra. Home > African Journals Online: Andorra. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online: Ireland

African Journals Online (AJOL)

African Journals Online: Ireland. Home > African Journals Online: Ireland. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access. Afghanistan ...

African Journals Online: Belgium

African Journals Online (AJOL)

African Journals Online: Belgium. Home > African Journals Online: Belgium. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online: Switzerland

African Journals Online (AJOL)

African Journals Online: Switzerland. Home > African Journals Online: Switzerland. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is Open Access ...

African Journals Online (AJOL)

African Journals Online (AJOL)

In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and to ... Ergonomics SA. Vol 9, No 1 (2017). Inkanyiso: Journal of Humanities and Social Sciences. Vol 14, No 5 (2017). Journal of Pharmaceutical and Allied Sciences.

African Journals Online (AJOL)

African Journals Online (AJOL)

In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans ... Global Journal of Geological Sciences. Vol 16, No 1 (2018). Sokoto Journal of Veterinary Sciences. Vol 7, No 1 (2017). Nigeria Journal of Pure and Applied Physics.

Archives: African Studies Monographs

African Journals Online (AJOL)

Archives: African Studies Monographs. Journal Home > Archives: African Studies Monographs. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 5 of 5 Items. 2007. Vol 8 (2007) ...

The African filmmaker and content of African films: a study of the perspectives of the Nigerian film audience

OpenAIRE

Ganivu Olalekan Akashoro

2011-01-01

This paper attempts to appraise African filmmaking and the content of African films from a Nigerian film audience perspective. The study specifically explores the disposition of the audience towards contemporary African filmmaking for home video and cinema entertainment as well as the content of African films. The study used a qualitative questionnaire to determine the perspectives of residents in Lagos as members of the Nigerian film audience. The study found the perception of the content of...

South African Music Studies: Editorial Policies

African Journals Online (AJOL)

SAMUS: South African Music Studies is the official organ for the South African Society for Research in Music (SASRIM). It gives priority to the publication of research on South African music, but continues to represent the wider field of research interests in the country and in the rest of Africa. The journal invites work from any ...

Radiation biology of mosquitoes

Directory of Open Access Journals (Sweden)

Knols Bart GJ

2009-11-01

Full Text Available Abstract There is currently renewed interest in assessing the feasibility of the sterile insect technique (SIT to control African malaria vectors in designated areas. The SIT relies on the sterilization of males before mass release, with sterilization currently being achieved through the use of ionizing radiation. This paper reviews previous work on radiation sterilization of Anopheles mosquitoes. In general, the pupal stage was irradiated due to ease of handling compared to the adult stage. The dose-response curve between the induced sterility and log (dose was shown to be sigmoid, and there was a marked species difference in radiation sensitivity. Mating competitiveness studies have generally been performed under laboratory conditions. The competitiveness of males irradiated at high doses was relatively poor, but with increasing ratios of sterile males, egg hatch could be lowered effectively. Males irradiated as pupae had a lower competitiveness compared to males irradiated as adults, but the use of partially-sterilizing doses has not been studied extensively. Methods to reduce somatic damage during the irradiation process as well as the use of other agents or techniques to induce sterility are discussed. It is concluded that the optimal radiation dose chosen for insects that are to be released during an SIT programme should ensure a balance between induced sterility of males and their field competitiveness, with competitiveness being determined under (semi- field conditions. Self-contained 60Co research irradiators remain the most practical irradiators but these are likely to be replaced in the future by a new generation of high output X ray irradiators.

Association of substance use disorders with childhood trauma but not African genetic heritage in an African American cohort.

Science.gov (United States)

Ducci, Francesca; Roy, Alec; Shen, Pei-Hong; Yuan, Qiaoping; Yuan, Nicole P; Hodgkinson, Colin A; Goldman, Lynn R; Goldman, David

2009-09-01

Genetic variation influences differential vulnerability to addiction within populations. However, it remains unclear whether differences in frequencies of vulnerability alleles contribute to disparities between populations and to what extent ancestry correlates with differential exposure to environmental risk factors, including poverty and trauma. The authors used 186 ancestry-informative markers to measure African ancestry in 407 addicts and 457 comparison subjects self-identified as African Americans. The reference group was 1,051 individuals from the Human Genome Diversity Cell Line Panel, which includes 51 diverse populations representing most worldwide genetic diversity. African Americans varied in degrees of African, European, Middle Eastern, and Central Asian genetic heritage. The overall level of African ancestry was actually smaller among cocaine, opiate, and alcohol addicts (proportion=0.76-0.78) than nonaddicted African American comparison subjects (proportion=0.81). African ancestry was associated with living in impoverished neighborhoods, a factor previously associated with risk. There was no association between African ancestry and exposure to childhood abuse or neglect, a factor that strongly predicted all types of addictions. These results suggest that African genetic heritage does not increase the likelihood of genetic risk for addictions. They highlight the complex interrelation between genetic ancestry and social, economic, and environmental conditions and the strong relation of those factors to addiction. Studies of epidemiological samples characterized for genetic ancestry and social, psychological, demographic, economic, cultural, and historical factors are needed to better disentangle the effects of genetic and environmental factors underlying interpopulation differences in vulnerability to addiction and other health disparities.

Association of African Universities : Education and Research ...

International Development Research Centre (IDRC) Digital Library (Canada)

Association of African Universities : Education and Research Networking Unit. The Association of African Universities (AAU), headquartered in Accra, Ghana, is an international nongovernmental organization (NGO) that promotes cooperation between African universities and with the international community.

Race, health, and the African Diaspora.

Science.gov (United States)

Spigner, Clarence

Health inequalities exist throughout the African Diaspora and are viewed in this article as largely color-coded. In developed, developing, and undeveloped nations today, "racial" stratification is consistently reflected in an inability to provide adequate health regardless of national policy or ideology. For instance, African Americans experience less than adequate health care very similar to Blacks in Britain, in spite of each nations differing health systems. Latin America's Africana Negra communities experience poorer health similar to Blacks throughout the Caribbean. The African continent itself is arguably the poorest on earth. A common history of racism correlates with health disparities across the African Diaspora.

African Journal of Biotechnology: Submissions

African Journals Online (AJOL)

PROMOTING ACCESS TO AFRICAN RESEARCH ... The African Journal of Biotechnology (AJB) (ISSN 1684-5315) provides rapid publication of .... Authors may still request (in advance) that the editorial board waive some of the handling fee ...

African Journals Online (AJOL)

African Journals Online (AJOL)

In partnership with hundreds of journals from all over the continent, AJOL works to change this, so that African-origin research output is available to Africans and to the rest of the world. AJOL is a Non-Profit Organisation based ... International Journal of Engineering, Science and Technology. Vol 4, No 1 (2012). International ...

Archives: African Health Sciences

African Journals Online (AJOL)

Items 1 - 50 of 67 ... Archives: African Health Sciences. Journal Home > Archives: African Health Sciences. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 50 of 67 Items, 1 2 > >> ...

African Journals Online: Nigeria

African Journals Online (AJOL)

Items 1 - 50 of 221 ... African Journal of Clinical and Experimental Microbiology ... The African Journal of Drug & Alcohol Studies is an international scientific journal ... d) Critical or analytical reviews in the area of theory, policy, or research in Dentistry. e) Reviews of recently published books or group of books which would be of ...

African Art Teaching Strategies.

Science.gov (United States)

Chanda, Jacqueline

Three different models for the teaching of African art are presented in this paper. A comparison of the differences between the approaches of Western art historians and African art historians informs the articulation of the three models--an approach for determining style, another for dealing with analysis, and a third for synthetic interpretation.…

African Cultural Astronomy

CERN Document Server

Holbrook, Jarita C; Medupe, R. Thebe; Current Archaeoastronomy and Ethnoastronomy research in Africa

2008-01-01

Astronomy is the science of studying the sky using telescopes and light collectors such as photographic plates or CCD detectors. However, people have always studied the sky and continue to study the sky without the aid of instruments this is the realm of cultural astronomy. This is the first scholarly collection of articles focused on the cultural astronomy of Africans. It weaves together astronomy, anthropology, and Africa. The volume includes African myths and legends about the sky, alignments to celestial bodies found at archaeological sites and at places of worship, rock art with celestial imagery, and scientific thinking revealed in local astronomy traditions including ethnomathematics and the creation of calendars. Authors include astronomers Kim Malville, Johnson Urama, and Thebe Medupe; archaeologist Felix Chami, and geographer Michael Bonine, and many new authors. As an emerging subfield of cultural astronomy, African cultural astronomy researchers are focused on training students specifically for do...

Effects of gamma radiation on bee venom: preliminary studies

Energy Technology Data Exchange (ETDEWEB)

Costa, H.; Boni-Mitake, M.; Souza, C.F.; Rogero, J.R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div. de Radiobiologia

1999-11-01

Africanized honeybees are very common insects in Brazil and frequently cause accidents followed by important immunological reactions and even deaths. Their venoms are composed of a complex mixture of substances of general biological actions. several works utilizing ionizing radiation showed that it is able to modify protein structures, and successfully detoxify snake venoms toxins, although maintaining its immunological properties. The main objective of this paper was to study the effects of gamma radiation on bee venom, regarding some biochemical and toxicological aspects. Africanized Apis melllifera whole venom (2 mg/ml) in 0.15 M Na Cl solution was irradiated with 2 kGy in a {sup 60} Co source. Preliminary studies has been carried out in order to identify some biochemical changes after irradiation. Concerning this, irradiated and native venom were submitted to a molecular exclusion chromatography (Sephadex G-100), UV absorption spectrum and protein concentration analysis. It could be seen that irradiated bee venom spectrum presented differences when compared to native bee venom, suggesting that some structural alterations has occurred. Protein concentration and chromatography profiles were not changes after irradiation. In order to evaluate the toxicity a lethality assay (L D{sub 50}) has been performed with both venoms, and irradiated venom showed to be less toxic than native one. (author) 23 refs., 3 figs., 1 tab.

Mental Health and African Americans

Science.gov (United States)

... Minority Population Profiles > Black/African American > Mental Health Mental Health and African Americans Poverty level affects mental health ... compared to 120% of non-Hispanic whites. 1 MENTAL HEALTH STATUS Serious psychological distress among adults 18 years ...

The impacts of the dust radiative effect on vegetation growth in the Sahel

Science.gov (United States)

Evans, S. M.; Shevliakova, E.; Malyshev, S.; Ginoux, P. A.

2017-12-01

Many studies have been conducted on the effects of dust on rainfall in the Sahel, and generally show that African dust weakens the West African Monsoon, drying the region. This drying is often assumed to reduce vegetation cover for the region, providing a positive feedback with dust emission. There are, however, other competing effects of dust that are also important to plant growth, including a reduction in surface temperature, a reduction in downwelling solar radiation, and an increase in the diffuse fraction of that solar radiation. Using the NOAA/GFDL CM3 model coupled to the dynamic vegetation model LM3, we demonstrate that the combined effect of all these processes is to decrease the vegetation coverage and productivity of the Sahel and West Africa. We accomplish this by comparing experiments with radiatively active dust to experiments with radiatively invisible dust. We find that in modern conditions, the dust radiative effect reduces the net primary productivity of West Africa and the Sahel by up to 30% locally, and when summed over the region accounts for a difference of approximately 0.4 GtC per year. Experiments where the vegetation experiences preindustrial rather than modern CO2 levels show that without carbon fertilization, this loss of productivity would be approximately 10% stronger. In contrast, during preindustrial conditions the vegetation response is less than half as strong, despite the dust induced rainfall and temperature anomalies being similar. We interpret this as the vegetation being less susceptible to drought in a less evaporative climate. These changes in vegetation create the possibility of a dust-vegetation feedback loop whose strength varies with the mean state of the climate, and which may grow stronger in the future.

The African Union and Conflict Management

Science.gov (United States)

2006-03-02

USAWC STRATEGY RESEARCH PROJECT THE AFRICAN UNION AND CONFLICT MANAGEMENT by Lieutenant Colonel Flemming Mathiasen Royal Danish Army Colonel Patrick...AUTHOR: Lieutenant Colonel Flemming Mathiasen TITLE: The African Union and Conflict Management FORMAT: Strategy Research Project DATE: 2 March 2006...WORD COUNT: 5850 PAGES: 28 KEY TERMS: African Union, Africa, Conflict Management , Capabilities CLASSIFICATION: Unclassified Africa is a continent with a

OGIRISI: a New Journal of African Studies: Editorial Policies

African Journals Online (AJOL)

Focus and Scope. OGIRISI is a multidisciplinary journal. Its principal scope definition is focus on Africa. It therefore welcomes articles that attend to the African world, existence and development; African worldview and values; African symbols and institutions; African situation and the globalizing world; African problems and ...

"Now the African reigns supreme": the rise of African boxing on the Witwatersrand, 1924-1959.

Science.gov (United States)

Fleming, Tyler

2011-01-01

This essay explores the growth of boxing among the African populations on the Witwatersrand region of South Africa between 1924 and 1959. It details how the sport's jump in popularity with Africans paralleled migration to Johannesburg. Africans increasingly saw boxing as an activity and skill conducive with survival in this new environment, and thus the sport grew in popularity, stature, and skill-level amongst this emergent urban population. The essay further explores the various ways that the sport was disseminated and popularized during the era, thus detailing how the sport reached both the African masses and petit-bourgeois educated elite. As their presence in Johannesburg became more and more permanent, boxing came to encompass various meanings and ideals, such as notions of discipline, independence and civility, to these urban populations.

KSC kicks off African-American History Month

Science.gov (United States)

2000-01-01

Clothed in her traditional African garb, Michelle Amos, mistress of ceremonies, welcomes the audience on Feb. 3 at the kick-off of African-American History Month. The theme for this year's observation is 'Heritage and Horizons: The African-American Legacy and the Challenges of the 21st Century.' February is designated each year as a time to celebrate the achievements and contributions of African Americans to Kennedy Space Center, NASA and the nation.

African Journal of Aquatic Science

African Journals Online (AJOL)

AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING ... The African Journal of Aquatic Science is an international journal devoted to the ... papers and short articles in all the aquatic science fields including limnology, ...

African Studies Monographs: Editorial Policies

African Journals Online (AJOL)

Focus and Scope. The African Studies Monographs is a serial that promotes research and scholarship on the African perspective worldwide. This includes matters of philosophy, history, literature, arts and culture, environment, gender, politics, administration crisis management, etc.

Contemporary African philosophy: emergent issues and challenges ...

African Journals Online (AJOL)

... all philosophies remain context-dependent and cultureoriented. A contrary view ignores the proper nature of philosophy. A new phenomenon confronts currently confronts all comers to contemporary African philosophy: an expansive vision of African philosophical discourse. Contemporary African philosophers attempt to ...

[African neurosurgery. 1: Historical outline].

Science.gov (United States)

el Khamlichi, A

1996-01-01

This outline of the history of African Neurosurgery explains the role that North Africa has played in the Middle Ages in the development of Neurosurgery, the origins of the development of the latter in twentieth century, and the delay that African Neurosurgery still shows at the present time in the majority of African countries. On the papyrus of the pharaonic era, we have found the description of some neurosurgical procedures such as trephination and brain aspiration by a transphenoidal approach used before mummification. It is particularly trephination which summarizes the ancient history of African neurosurgery, as it was widely used throughout the continent, practised and taught by healers in African tribes. The technical concepts of trephination are based, to a great extent, on the descriptions of Arab physicians of the Middle Ages. It was at that time (Middle Ages) that several Arab physicians such as Avicenne, Rhazes, and Avenzhoer described many types of nervous system diseases and the techniques to treat them. But it was mainly Abulkassim Al Zahraoui (Abulkassis) who was the pioneer of neurosurgery as he devoted one volume of his treatise (made up of 30 volumes) to neurosurgery, a precise description of many aspects of neurosurgical pathology, its treatment, instruments and neurosurgical techniques. We have reported in this article five original extracts in Arabic which deal with skull fractures and their treatment, vertebro-medullary traumas and their treatment, hydrocephalus and its treatment, tumors of the skull vault and their treatment, and finally the basic knowledge of anatomy which is of great interest for a surgeon. The medical knowledge of that time which gave birth to medical schools and hospitals was transmitted progressively to Europe and played an important role in the development of medicine during the European Renaissance in the fifteenth and sixteenth centuries. During colonization, neurosurgical practice started and developed in many

Preliminary gut content and dentition analysis reveal subtle resource ...

African Journals Online (AJOL)

The trophic relationships between six haplochromine cichlids of Lake Kanyaboli, a satellite lake of Lake Victoria that has not been infested by the Nile perch (Lates niloticus), were studied as a first step towards understanding the cichlid community structure in this threatened wetland ecosystem. Coefficient of similarity ...

Lateralized Feeding Behavior is Associated with Asymmetrical Neuroanatomy and Lateralized Gene Expressions in the Brain in Scale-Eating Cichlid Fish.

Science.gov (United States)

Lee, Hyuk Je; Schneider, Ralf F; Manousaki, Tereza; Kang, Ji Hyoun; Lein, Etienne; Franchini, Paolo; Meyer, Axel

2017-11-01

Lateralized behavior ("handedness") is unusual, but consistently found across diverse animal lineages, including humans. It is thought to reflect brain anatomical and/or functional asymmetries, but its neuro-molecular mechanisms remain largely unknown. Lake Tanganyika scale-eating cichlid fish, Perissodus microlepis show pronounced asymmetry in their jaw morphology as well as handedness in feeding behavior-biting scales preferentially only from one or the other side of their victims. This makes them an ideal model in which to investigate potential laterality in neuroanatomy and transcription in the brain in relation to behavioral handedness. After determining behavioral handedness in P. microlepis (preferred attack side), we estimated the volume of the hemispheres of brain regions and captured their gene expression profiles. Our analyses revealed that the degree of behavioral handedness is mirrored at the level of neuroanatomical asymmetry, particularly in the tectum opticum. Transcriptome analyses showed that different brain regions (tectum opticum, telencephalon, hypothalamus, and cerebellum) display distinct expression patterns, potentially reflecting their developmental interrelationships. For numerous genes in each brain region, their extent of expression differences between hemispheres was found to be correlated with the degree of behavioral lateralization. Interestingly, the tectum opticum and telencephalon showed divergent biases on the direction of up- or down-regulation of the laterality candidate genes (e.g., grm2) in the hemispheres, highlighting the connection of handedness with gene expression profiles and the different roles of these brain regions. Hence, handedness in predation behavior may be caused by asymmetric size of brain hemispheres and also by lateralized gene expressions in the brain. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

AFRICAN BUFFALO OPTIMIZATION ico-pdf

Directory of Open Access Journals (Sweden)

Julius Beneoluchi Odili

2016-02-01

Full Text Available This is an introductory paper to the newly-designed African Buffalo Optimization (ABO algorithm for solving combinatorial and other optimization problems. The algorithm is inspired by the behavior of African buffalos, a species of wild cows known for their extensive migrant lifestyle. This paper presents an overview of major metaheuristic algorithms with the aim of providing a basis for the development of the African Buffalo Optimization algorithm which is a nature-inspired, population-based metaheuristic algorithm. Experimental results obtained from applying the novel ABO to solve a number of benchmark global optimization test functions as well as some symmetric and asymmetric Traveling Salesman’s Problems when compared to the results obtained from using other popular optimization methods show that the African Buffalo Optimization is a worthy addition to the growing number of swarm intelligence optimization techniques.

The UCAR Africa Initiative: Enabling African Solutions to African Needs

Science.gov (United States)

Pandya, R.; Bruintjes, R.; Foote, B.; Heck, S.; Hermann, S.; Hoswell, L.; Konate, M.; Kucera, P.; Laing, A.; Lamptey, B.; Moncrieff, M.; Ramamurthy, M.; Roberts, R.; Spangler, T.; Traoré, A.; Yoksas, T.; Warner, T.

2007-12-01

The University Corporation for Atmospheric Research (UCAR) Africa Initiative (AI) is a coordinated effort aimed at building sustainable partnerships between UCAR and African institutions in order to pursue research and applications for the benefit of the African people. The initiative is based on four fundamental operating principles, concisely summarized by the overall philosophy of enabling African solutions to African needs. The four principles are: • Collaborate with African institutions • Focus on institutional capacity building and research support • Explore science research themes critical to Africa and important for the world • Leverage the research infrastructure in UCAR to add value These principles are realized in a set of pilot activities, chosen for their high probability of short-term results and ability to set the stage for longer-term collaboration. The three pilot activities are listed below. 1. A modest radar network and data-distribution system in Mali and Burkina Faso, including a data-sharing MOU between the Mail and Burkina Faso Weather Services. 2. A partnership among UCAR, the Ghana Meteorological Agency, and the Ghana university community to develop an operational Weather Research and Forecasting (WRF) model for West Africa. The output is used by researchers and operational forecasters in Africa. Model output is also part of a demonstration project that aims to allow humanitarian agencies to share geo-referenced information in Africa via a web portal. 3. A workshop in Ouagadougou, Burkina Faso from April 2-6, 2007, with the theme Improving Lives by Understanding Weather. The workshop, co-organized with Programme SAAGA and the Commité Permanent Inter-Etats de Lutte Contre la Sécheresse dans le Sahel (CILSS), included over 80 participants from 18 countries, and produced a set of recommendations for continued collaboration. Our presentation will provide an update of these pilot activities and point to future directions. Recognizing

A Call to African Unity

DEFF Research Database (Denmark)

Muchie, Mammo

This month's paper, written by Professor Mammo Muchie, examines the necessity for a pan-African monetary union.  Professor Muchie argues for the "the creation of a unified African strategy and unified approach to dealing with the outside donor world by neutralising the poison of money as honey...... that donor aid has come to be in Africa." He provides a historic and contemporary context for the unification of monetary and customs systems across Africa and argues for a dual currency system for the self-financing of African development and for sustained self-determination....

Consequences of the African Diaspora on Nutrition

OpenAIRE

Okonkwo, Sharon K.

2002-01-01

African-Americans, Afro-Carribeans and other children of the African diaspora continue to fare worse in many health measures of diet, nutrition, morbidity and mortality. What are some of the nutritional basis of such an outcome? What factors exist in the diet of these groups of people that have prevented them from obtaining the health outcomes of their predecessors? The African Diaspora is responsible for a huge transformation and translocation of millions of Africans during a four hundred ye...

Changing Fatherhood: An Exploratory Qualitative Study with African and African Caribbean Men in England

Science.gov (United States)

Williams, Robert; Hewison, Alistair; Wildman, Stuart; Roskell, Carolyn

2013-01-01

This paper presents findings from a qualitative study undertaken with 46 African and African Caribbean men exploring their experiences of fatherhood. Data analysis was informed by Connell's theoretical work on changing gender relations. Findings indicate that fathers' lives were mediated by masculinities, racism, gender, migration and generational…

Educational Adaptation and Pan-Africanism: Trends in Africa.

Science.gov (United States)

Marah, John Karefah

1987-01-01

European colonialists believed that Africans should be educated in African traditional values, and that Africans should be made into dedicated workers, not holders of power. The African nationalists of the 1960s, in contrast, rejected most of the arduous aspects of European education as instruments of domination, and lay the foundation for the…

Radiation and convective heat transfer, and burnout in oxy-coal combustion

Energy Technology Data Exchange (ETDEWEB)

J.P. Smart; P. O' Nions; G.S. Riley [RWE npower, Swindon (United Kingdom)

2010-09-15

Measurements of radiative and convective heat transfer, and carbon-in-ash have been taken on the RWEn 0.5 MWth combustion test facility (CTF) firing two different coals under oxy-fuel firing conditions. The two coals fired were a Russian Coal and a South African Coal. Recycle ratios were varied within the range of 65-75% dependent on coal. Furnace exit O{sub 2} values were maintained at 3% and 6% for the majority of tests. Air firing tests were also performed to generate baseline data. The work gives a comprehensive insight into the effect of oxy-fuel combustion on both radiative and convective heat transfer, and carbon-in-ash compared to air under dry simulated recycle conditions. Results have shown peak radiative heat flux values are inversely related to the recycle ratio for the two coals studied. Conversely, the convective heat flux values increase with increasing recycle ratio. It was also observed that the axial position of the peak in radiative heat flux moves downstream away from the burner as recycle ratio is increased. A 'working range' of recycle ratios exists where both the radiative and convective heat fluxes are comparable with air. Carbon-in-ash (CIA) was measured for selected conditions. For air firing of Russian Coal, the CIA for follows and expected trend with CIA decreasing with increasing furnace exit O{sub 2}. The CIA data for the two recycle ratios of 72% and 68% for the same coal show that the CIA values are lower than for air firing for corresponding furnace exit O{sub 2} levels and vary little with the value of furnace exit O{sub 2}. CIA measurements were taken for the South African Coal for a range of recycle ratios at 3% and 6% furnace exit O{sub 2} levels. Results indicate that the CIA values are lower for higher furnace exit O{sub 2}. 32 refs., 11 figs., 1 tab.

The Impact of the African Growth and Opportunity Act (AGOA): An Empirical Analysis of Sub-Saharan African Agricultural Exports

OpenAIRE

Zenebe, Addisalem; Peterson, Wesley; Wamisho, Kassu

2014-01-01

The African Growth and Opportunities Act (AGOA) which was signed into law in 2000 as part of U.S. trade legislation has the objectives of increasing trade and investment between the U.S. and eligible Sub-Saharan African (SSA) countries, by reducing or eliminating tariffs applied to African exports of different products. This Act represents a promising approach to economic growth and development in SSA through international trade. This research paper examines the impact of AGOA on African agri...

Understanding the Strengths of African American Families.

Science.gov (United States)

Littlejohn-Blake, Sheila M.; Darling, Carol Anderson

1993-01-01

Focuses on strengths of African-American families and how they function, relevant conceptual approaches, and trends and issues in studying African-American families that can facilitate understanding. A shift from studying dysfunctional families to more positive aspects can help African-American families meet societal challenges. (SLD)

African Philosophy and Development: A Contemporary Perspective ...

African Journals Online (AJOL)

... socio-political, scientific and technological. In all these facets of development, Africa and the Africans have made tremendous contributions. Africans, through their reflective attitudes to society, environment and nature have helped to add value to changes, improvement and innovations of African societies and the world at ...

Engaging African Americans in Smoking Cessation Programs

Science.gov (United States)

Wallen, Jacqueline; Randolph, Suzanne; Carter-Pokras, Olivia; Feldman, Robert; Kanamori-Nishimura, Mariano

2014-01-01

Background: African Americans are disproportionately exposed to and targeted by prosmoking advertisements, particularly menthol cigarette ads. Though African Americans begin smoking later than whites, they are less likely to quit smoking than whites. Purpose: This study was designed to explore African American smoking cessation attitudes,…

Accessibility perspectives on enabling South African sign language in the South African National Accessibility Portal

CSIR Research Space (South Africa)

Coetzee, L

2009-04-01

Full Text Available and services. One such mechanism is by embedding animated Sign Language in Web pages. This paper analyses the effectiveness and appropriateness of using this approach by embedding South African Sign Language in the South African National Accessibility Portal...

Genome-Wide Association Study to Identify Single Nucleotide Polymorphisms (SNPs) Associated With the Development of Erectile Dysfunction in African-American Men After Radiotherapy for Prostate Cancer

International Nuclear Information System (INIS)

Kerns, Sarah L.; Ostrer, Harry; Stock, Richard; Li, William; Moore, Julian; Pearlman, Alexander; Campbell, Christopher; Shao Yongzhao; Stone, Nelson; Kusnetz, Lynda; Rosenstein, Barry S.

2010-01-01

Purpose: To identify single nucleotide polymorphisms (SNPs) associated with erectile dysfunction (ED) among African-American prostate cancer patients treated with external beam radiation therapy. Methods and Materials: A cohort of African-American prostate cancer patients treated with external beam radiation therapy was observed for the development of ED by use of the five-item Sexual Health Inventory for Men (SHIM) questionnaire. Final analysis included 27 cases (post-treatment SHIM score ≤7) and 52 control subjects (post-treatment SHIM score ≥16). A genome-wide association study was performed using approximately 909,000 SNPs genotyped on Affymetrix 6.0 arrays (Affymetrix, Santa Clara, CA). Results: We identified SNP rs2268363, located in the follicle-stimulating hormone receptor (FSHR) gene, as significantly associated with ED after correcting for multiple comparisons (unadjusted p = 5.46 x 10 -8 , Bonferroni p = 0.028). We identified four additional SNPs that tended toward a significant association with an unadjusted p value -6 . Inference of population substructure showed that cases had a higher proportion of African ancestry than control subjects (77% vs. 60%, p = 0.005). A multivariate logistic regression model that incorporated estimated ancestry and four of the top-ranked SNPs was a more accurate classifier of ED than a model that included only clinical variables. Conclusions: To our knowledge, this is the first genome-wide association study to identify SNPs associated with adverse effects resulting from radiotherapy. It is important to note that the SNP that proved to be significantly associated with ED is located within a gene whose encoded product plays a role in male gonad development and function. Another key finding of this project is that the four SNPs most strongly associated with ED were specific to persons of African ancestry and would therefore not have been identified had a cohort of European ancestry been screened. This study demonstrates

African Voices and Activists at the WSF in Nairobi: The Uncertain Ways of Transnational African Activism

Directory of Open Access Journals (Sweden)

Marie-Emmanuelle Pommerolle

2015-08-01

Full Text Available Transnational social movement studies have long neglected the way activists from the South, and particularly from Africa, have participated in World Social Forum processes. Alterglobal activists have also been accused of neglecting or dominating southern voices. The organization of the WSF in Nairobi was seen as an opportunity to make African voices be heard. This examines how Africans activists participated in Nairobi, and the complex relationship they have to northern and other southern (such as Asia and Latin America activists. The African alterglobal movement is seen as a space of tensions (i.e. between South Africans and the rest of the continent, between French and English speaking Africa, or between NGOs and more radical organizations reflected in national mobilizations. Our team of 23 French and 12 Kenyan scholars made collective ethnographic observations in more than a hundred workshops and conducted 150 biographical interviews of African activists in order to examine how: Africa was referred to in the WSF; activists financed their trip to Nairobi; and Afrocentric, anti-imperialist, and anticolonial arguments have been used.

Mechanisms of Saharan Dust Radiative Effects Coupled to Eddy Energy and Wave Activity

Science.gov (United States)

Hosseinpour, F.; Wilcox, E. M.; Colarco, P. R.

2017-12-01

We explore mechanisms addressing the relationships between the net radiative forcing of Saharan Air Layer (SAL) and eddy energetics of the African Easterly jet-African easterly wave (AEJ-AEWs) system across the tropical Atlantic storm track. This study indicates that radiatively interactive dust aerosols have the capability to modify the exchange of kinetic energy between the AEWs and AEJ. We find that while dust can have both constructive and destructive effects on eddy activity of the waves, depending on the behavior and structure of waves exhibiting different characteristic time-scales, the local heating by dust tends to change the quadruple pattern of eddy momentum fluxes of the AEWs which can yield feedbacks onto the mean-flow. These results arise from applying an ensemble of large NASA satellite observational data sets, such as MODIS, SeaWiFS and TRMM, as well as the GOCART aerosol model and MERRA reanalysis. Sensitivity studies indicate that the results are consistent when the analysis is performed with multiple different aerosol datasets. While the mechanisms proposed here require further evaluation with numerical model experiments, this study presents a novel approach and new insights into Saharan dust effects on large-scale climate dynamics.

A Relevant Education for African Development—Some ...

African Journals Online (AJOL)

Education in Africa has been and mostly remains a journey fuelled by an exogenously induced and internalised sense of inadequacy in Africans, and endowed with the mission of devaluation or annihilation of African creativity, agency and value systems. Such cultural estrangement has served to reinforce in Africans ...

African Journals Online: Fish & Fisheries

African Journals Online (AJOL)

The African (formerly South African) Journal of Marine Science provides an international forum for the publication of original scientific contributions or critical reviews, involving oceanic, shelf or estuarine waters, inclusive of oceanography, studies of organisms and their habitats, and aquaculture. Papers on the conservation ...

Mgbakoigba: Journal of African Studies

African Journals Online (AJOL)

... approaching history, methodology and theory in African knowledge production. Considering new frameworks for reflecting and addressing issues arising from ... All work submitted are subject to peer review. ... The legacies of the foremost patriots of African nationalism · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

South African Gastroenterology Review: Journal Sponsorship

African Journals Online (AJOL)

South African Gastroenterology Review: Journal Sponsorship. Journal Home > About the Journal > South African Gastroenterology Review: Journal Sponsorship. Log in or Register to get access to full text downloads.

African Journals Online: Browse Alphabetically -- letter A

African Journals Online (AJOL)

Items 1 - 50 of 93 ... African Journal of AIDS Research (AJAR) is a peer-reviewed ... The African Journal of Aquatic Science is an international journal ... Later, the need to expand the horizon of the journal led to the formation of a group (Biomedical Communications ... African Journal of Clinical and Experimental Microbiology.

AFRICAN SOLUTIONS TO AFRICA'S PROBLEMS? AFRICAN ...

African Journals Online (AJOL)

Ilse van der Walt

foreign policy challenge from which most others will ultimately emanate.46 .... African politics easily degenerates into a life-and-death struggle over private ... material interest and power balancing dominate as “predictability based on a set of ..... Due to its proximity to conflict areas, civil society has been able to work at.

LEADERSHIP AS IDENTITY: THE FOCUS IN AFRICAN LITERATURE

Directory of Open Access Journals (Sweden)

Karin Ilona Paasche

2017-04-01

Full Text Available The "Panama Papers" leakage implicated several African leaders in global corruption deals. It confirmed perceptions that these leaders care little for their people. African leaders who overstay term limits are the focus of Western democratic ire. Pro-democracy movements, the overthrow of regimes characterised as undemocratic gain unquestioned media coverage and praise. African leaders are summoned to the International Criminal Court in The Hague; their societies debate whether justice can be administered from outside. Increasingly, voices question African political and developmental processes. African Literature participates in struggles defining modern Africa’s search for identity and its own definition of leadership. It points to possibilities rooted in African Oral Tradition and in customs predating various colonial systems. Leadership forms that societies choose are closely linked to perceptions of identity. This paper examines the crisis of identity which has resulted in Africa’s crisis of leadership and looks at approaches taken by African writers and filmmakers: Malian filmmaker Cheik Oumar Sissoko’s film "La Genèse" (1999, South African writer Zakes Mda’s novels "Ways of Dying" (1995, "Heart of Redness" (2000.

African Journal of Paediatric Nephrology

African Journals Online (AJOL)

African Journal of Paediatric Nephrology is the official Journal of the African Paediatric Nephrology Association (AFPNA). The journal is dedicated to increasing awareness and knowledge of Paediatric nephrology in Africa and beyond. We publish research articles on renal diseases in children, on fluid and electrolyte ...

Southern African Journal of Environmental Education

African Journals Online (AJOL)

... knowledge and community based management of wildlife resources: a study of the Mumbwa and Lupande Game Management areas of Zambia. ... Southern African Journal of Environmental Education ... AJOL African Journals Online.

PREVALENCE OF BENIGN PROSTATIC HYPERPLASIA AND PROSTATE CANCER IN AFRICANS AND AFRICANS IN THE DIASPORA.

Science.gov (United States)

Yeboah, E D

2016-01-01

There have been several publications on population or community prevalence of benign prostatic hyperplasia and prostate cancer from various countries and races but few reports are from Africa on Africans. A review on the prevalence of benign prostatic hyperplasia and prostate cancer in Africans and other races. The current literature on prevalence of benign prostatic hyperplasia (BPH), prostate cancer (PC), and benign prostatic hyperplasia co-existing with prostate cancer in Africans and other races is reviewed. Benign prostatic hyperplasia (BPH) prevalence in Ghana is responsible for 60% acute retention of urine and 28.6% of haematuria. Worldwide prevalence of BPH varies from 20 - 62% in men over 50 years and this includes USA, UK, Japan and Ghana. Reports from South Africa indicate prevalence of over 50% in adult males of 60 years. BPH co-existing with PC - Reports from USA, UK and Japan and Ghana reveal moderate association of BPH and PC. The co-existence of PC in patients being treated for BPH is 3 - 20% Prostate Cancer prevalence - There is high prevalence in USA, Scandinavian Countries, African Americans (AA) and Caribbean blacks. Ghana, Trinidad & Tobago have reported high prevalence of 6 -10% in men aged 50 years and above but others reported low prevalence in Africans from Africa. The low reporting from Africa of 10 - 40:100,000 is attributable to under reporting, absence of PSA screening/testing, lack of reliable cancer registries and poor medical facilities. Economic Costs of BPH and PC: BPH in the USA national direct costs are estimated at U$4Billion and individual costs of US$1536 annually. In Ghana, individual costs for BPH medications range from US$300 - 550 per year and cost for simple prostatectomy/TURP is estimated at US$1100. For prostate cancer, individual direct costs from Europe range from 6,575 - 12,000 euros, £2818.00 UK and over U$12,000 - 20,000 in USA per annum. In Ghana, individual direct costs ranges, for radical prostatectomy and

Africans Consuming Hair, Africans Consumed by Hair

African Journals Online (AJOL)

... are anything to go by, Africans, it seems to us, are more amenable to flexible, ... to recognise and provide for the present absences and the absent presences of ... Beauty is as much a work of nature as it is the outcome of working on nature.

MORALITY AND RELIGION IN AFRICAN THOUGHT

African Journals Online (AJOL)

mode of African knowledge construction within indigenous communities. ... when one grants space for hybrid moral constructions between Christianity and ..... es the opinion that African cultural beliefs and practices exhibit an ontological.

African Journal of Neurological Sciences

African Journals Online (AJOL)

African Journal of Neurological Sciences (AJNS) is owned and controlled by the Pan African Association of Neurological Sciences (PAANS). The AJNS's aim is to publish scientific papers of any aspects of Neurological Sciences. AJNS is published quarterly. Articles submitted exclusively to the AJNS are accepted if neither ...

South African Journal of Botany

African Journals Online (AJOL)

The South African Journal of Botany, the official journal of the South African Association of Botanists publishes papers which make an original contribution to any field of Botany. Papers are accepted on the understanding that their contents have not been published, or submitted for publication, elsewhere. All submitted ...

Low Incidence of Fatigue after Hypofractionated Stereotactic Body Radiation Therapy (SBRT for Localized Prostate Cancer

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Chiranjeev eDash

2012-10-01

Full Text Available Background: Fatigue is a common side-effect of conventional prostate cancer radiation therapy. The increased delivery precision necessitated by the high dose per fraction of stereotactic body radiation therapy (SBRT offers the potential of reduce target volumes and hence the exposure of normal tissues to high radiation doses. Herein, we examine the level of fatigue associated with SBRT treatment.Methods: Forty patients with localized prostate cancer treated with hypofractionated SBRT, and a minimum of 12 months follow-up were included in this analysis. Self-reported fatigue and other quality of life measures were assessed at baseline and at 1, 3, 6, 9, and 12 months post-SBRT.Results: Mean levels of fatigue were elevated at 1 month post-SBRT compared to baseline values (p=0.02. Fatigue at the 3-month follow-up and later were higher but not statistically significantly different compared to baseline. African-American patients reported higher fatigue post-SBRT than Caucasian patients. Fatigue was correlated with hormonal symptoms as measured by the Expanded Prostate Cancer Index Composite (EPIC quality of life questionnaire, but not with urinary, bowel, or sexual symptoms. Age, co-morbidities, smoking, prostate specific antigen (PSA levels, testosterone levels, and tumor stage were not associated with fatigue. Conclusion: This is the first study to investigate fatigue as a side-effect of SBRT. In contrast to standard radiation therapy, results suggest SBRT-related fatigue is short-term rather than a long-term side effect of SBRT. These results also suggest post-SBRT fatigue to be a more frequent complication in African-Americans than Caucasians.

From union of tyrants to power to the people? The significance of the Pan-African Parliament for the African Union

NARCIS (Netherlands)

Walraven, van K.

2004-01-01

This article analyses the significance of the newly established Pan-African Parliament. As one of the few genuinely new institutions of the African Union (AU) - itself the successor of the Organization of African Unity (OAU) -, the Parliament's birth could provide the institutional transformations

Regional radiative impacts of mixed dust and carbonaceous aerosols over West Africa

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Malavelle, Florent; Pont, Véronique; Solmon, Fabien; Mallet, Marc; Léon, Jean-François; Liousse, Catherine; Johnson, Ben

2010-05-01

Africa is a major source of aerosols at global scale. Two types of aerosols dominate the regional background: biomass burning aerosols as results of combustion of the vegetation and mineral dust aerosols related to erosion of arid soils by wind. These important burdens of aerosols are known to have each one a strong impact on the regional radiative budget. Whereas recent modelling efforts show significant impacts at climatic timescale on West African Monsoon due to the radiative effects of dust aerosols (see Solmon et al 2008 in GRL and references therein), biomass burning radiative effects in this region stand still poorly documented. What about West Africa, during the dry season (december-february) when both biomass burning and dust aerosols are encountered in the atmospheric background ? In that frame, we use ICTP Regional Climate Model versions 3 in order to estimate the radiative forcing due to the external mixing of mineral dust and carbonaceous aerosols from biomass burning, BioFuel and Fossil Fuel combustion during the dry season. Emissions of biomass burning aerosols are taken from new inventories based on SPOT vegetation burnt area products. Optical properties of carboneaceous aerosols are updated thanks to chemical sampling at Djougou during AMMA SOP-0. This presentation focuses on the model efficiency to correctly reproduce the main features concerning aerosols observed during AMMA-SOP0/DABEX field campaigns. It refers to (i) a strong stratification of dust and smoke layers, and (ii) a marked seasonal cycle of aerosol mixture optical properties. Those features are key parameters for modelling the direct and semi direct effects of aerosols over West Africa. Results of simulations indicate that the particular low value of single scattering albedo (SSA) for biomass burning aerosols (~0.81 at 550nm) involves important diabatic heating in the atmosphere. Values of aerosol heating rates are estimated and compared with aircraft measurement from DABEX

Joint effects of pesticides and ultraviolet-B radiation on amphibian larvae

International Nuclear Information System (INIS)

Yu, Shuangying; Wages, Mike; Willming, Morgan; Cobb, George P.; Maul, Jonathan D.

2015-01-01

A combination of multiple stressors may be linked to global amphibian declines. Of these, pesticides and UVB radiation co-exposures were examined on the African clawed frog (Xenopus laevis) to provide information that may be useful for amphibian conservation. The independent action model and inferential statistics were used to examine interactions between pesticides (malathion, endosulfan, α-cypermethrin, or chlorothalonil) and environmentally relevant UVB exposures. UVB radiation alone caused 35–68% mortality and nearly 100% of malformations. Pesticides and UVB had additive effects on larval mortality; however, several non-additive effects (antagonistic and synergistic interactions) were observed for total body length. Insecticides mainly affected axial development, whereas UVB radiation caused high incidence of edema, gut malformations, and abnormal tail tips. These results suggest that sublethal developmental endpoints were more sensitive for detecting joint effects. This work has implications for amphibian risk assessments for ecosystems where pesticides and high UVB radiation may co-occur. - Highlights: • Interactive effects of UVB radiation-pesticide co-exposures were examined in frogs. • UVB radiation alone caused 35–68% mortality and nearly 100% of malformations. • Pesticides and UVB had additive effects on larval mortality. • Several non-additive effects were observed for total body length. • Amphibian risk assessments should consider UVB radiation exposure as a co-stressor. - Possible interactions between pesticides and UVB radiation support the idea that amphibian risk assessments should consider these co-stressors when high UVB radiation exposure is high.

"Brothers Gonna Work It Out:" Understanding the Pedagogic Performance of African American Male Teachers Working with African American Male Students

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Brown, Anthony L.

2009-01-01

Drawing from ethnographic data, this paper explores how African American male teachers working with African American male students performed their pedagogy. This paper highlights how teachers' understanding of African American males social and educational needs shaped their pedagogical performance. Interestingly however, teachers' performance was…

African Americans and High Blood Pressure

Science.gov (United States)

ANSWERS by heart Lifestyle + Risk Reduction High Blood Pressure What About African Americans and High Blood Pressure? African Americans in the U.S. have a higher prevalence of high blood pressure (HBP) than ...

Teaching African American Youth: Learning from the Lives of Three African American Social Studies Teachers

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McBride, Chantee Earl

2010-01-01

This study examines the life histories of three African American social studies teachers, focusing on the evolution and changes in their identities, perspectives, and attitudes related to their profession and instructional practice. In addition, the study addresses the significance of the teachers' racialized experiences as African Americans and…

The Great Migration and African-American Genomic Diversity.

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Soheil Baharian

2016-05-01

Full Text Available We present a comprehensive assessment of genomic diversity in the African-American population by studying three genotyped cohorts comprising 3,726 African-Americans from across the United States that provide a representative description of the population across all US states and socioeconomic status. An estimated 82.1% of ancestors to African-Americans lived in Africa prior to the advent of transatlantic travel, 16.7% in Europe, and 1.2% in the Americas, with increased African ancestry in the southern United States compared to the North and West. Combining demographic models of ancestry and those of relatedness suggests that admixture occurred predominantly in the South prior to the Civil War and that ancestry-biased migration is responsible for regional differences in ancestry. We find that recent migrations also caused a strong increase in genetic relatedness among geographically distant African-Americans. Long-range relatedness among African-Americans and between African-Americans and European-Americans thus track north- and west-bound migration routes followed during the Great Migration of the twentieth century. By contrast, short-range relatedness patterns suggest comparable mobility of ∼15-16km per generation for African-Americans and European-Americans, as estimated using a novel analytical model of isolation-by-distance.

Geoconservation - a southern African and African perspective

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Reimold, Wolf Uwe

1999-10-01

In contrast to Europe, where geoconservation is actively pursued in most countries and where two international symposia on this subject have been staged in 1991 and 1996, geoconservation in Africa has indeed a very poor record. Considering the wealth of outstanding geological sites and the importance African stratigraphy has within the global geological record, pro-active geoconservation on this continent has not featured very prominently to date. In the interest of science, education and tourism, unique and typical geosites need to be identified, catalogued, and prioritised with the aim being their protection. Most African countries do not have vibrant non-governmental organisations such as a strong geological society, which could drive projects like geoconservation, or strong support from the private sector for environmental work. Here, a case is made for the role that established National Geological Surveys, some of which are already involved with retroactive environmental geological work, could play in the forefront of pro-active geoconservation and site protection.

Toward a Caribbean psychology: an African-centered approach.

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Sutherland, Marcia Elizabeth

2011-01-01

Although the Americas and Caribbean region are purported to comprise different ethnic groups, this article’s focus is on people of African descent, who represent the largest ethnic group in many countries. The emphasis on people of African descent is related to their family structure, ethnic identity, cultural, psychohistorical, and contemporary psychosocial realities. This article discusses the limitations of Western psychology for theory, research, and applied work on people of African descent in the Americas and Caribbean region. In view of the adaptations that some people of African descent have made to slavery, colonialism, and more contemporary forms of cultural intrusions, it is argued that when necessary, notwithstanding Western psychology’s limitations, Caribbean psychologists should reconstruct mainstream psychology to address the psychological needs of these Caribbean people. The relationship between theory and psychological interventions for the optimal development of people of African descent is emphasized throughout this article. In this regard, the African-centered and constructionist viewpoint is argued to be of utility in addressing the psychological growth and development of people of African descent living in the Americas and Caribbean region.

African Journal of Science and Technology

African Journals Online (AJOL)

PROMOTING ACCESS TO AFRICAN RESEARCH ... The African Journal of Science and Technology (AJST) is a biannual technical publication ... Le Journal Africain de Science et de Technologie est une revue scientifique du Journal Africain ...

114 African Languages and African Literature Cecilia A. Eme ...

African Journals Online (AJOL)

Ike Odimegwu

multidimensional realizations which are represented in ideas, beliefs, and oral and ... broadly literature in African languages, literature in European languages etc. ..... death and language maintenance: Theoretical, practical and descriptive ...

South African Journal of Surgery

African Journals Online (AJOL)

The South African Journal of Surgery is published by the South African Medical Association and publishes papers related to surgery. Other websites related to this journal: http://www.sajs.org.za/index.php/sajs. Vol 56, No 1 (2018). DOWNLOAD FULL TEXT Open Access DOWNLOAD FULL TEXT Subscription or Fee Access ...

Elder Abuse among African Americans

Science.gov (United States)

Tauriac, Jesse J.; Scruggs, Natoschia

2006-01-01

Perceptions of extreme, moderate, and mild forms of elder abuse among African-American women (n=25) and men (n=10) were examined. African-American respondents emphasized physical abuse when giving examples of extremely abusive behavior. Along with physical abuse, verbal abuse was the most frequently identified form of abuse, and was significantly…

African Journals Online: Brunei Darussalam

African Journals Online (AJOL)

African Journals Online: Brunei Darussalam. Home > African Journals Online: Brunei Darussalam. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Browse By Category · Browse Alphabetically · Browse By Country · List All Titles · Free to read Titles This Journal is ...

South African Music Studies: Submissions

African Journals Online (AJOL)

SAMUS: South African Music Studies is accredited with the South African ... Only one submission at a time per author will be considered. 2. Articles ... The Editor reserves the right to make language and punctuation changes and other ... We may require a subvention (page fees) from authors of articles to cover printing costs.

AFRICAN JOURNAL OF ECONOMIC REVIEW

African Journals Online (AJOL)

Dr Kazungu

African Journal of Economic Review, Volume IV, Issue 1, January 2016 ... infant mortality rates in 31 selected sub-Saharan African countries for the .... Also, declines in nutritional status as a result of upsurge in food prices may cause poor birth ..... Deaton, A. (1989) 'Rice Prices and Income Distribution in Thailand: A Non- ...

Southern African Journal of Environmental Education

African Journals Online (AJOL)

The Southern African Journal of Environmental Education (SAJEE) is an accredited and ... It is published at least once a year, by the Environmental Education Association of Southern Africa (EEASA). ... AJOL African Journals Online. HOW TO ...

Dietary Fat and Vitamin E in Prostate Cancer Risk Among African Americans and Africans: A Case-Control Study

Science.gov (United States)

2007-02-01

ns ɘ.001 Table 5: Pattern of consumption of ice cream, yogurt , salad dressing & mayonnaise in the past three months by ethnic subgroup...Food Item African- Americans African Migrants African Nigerians Total 947 p-value Ice Cream/ Yogurt Regular Low fat Fat...p-value Corn Flour 200 (80.6) 35 (60.3) 537 (83.8) 771 (81.4) ɘ.001 Corn Flour Form Corn Bread Corn Pudding * Fermented Pudding

Africanization in the United States: Replacement of Feral European Honeybees (Apis mellifera L.) by an African Hybrid Swarm

OpenAIRE

Pinto, M. Alice; Rubink, William L.; Patton, John C.; Coulson, Robert N.; Johnston, J. Spencer

2005-01-01

The expansion of Africanized honeybees from South America to the southwestern United States in 50 years is considered one of the most spectacular biological invasions yet documented. In the American tropics, it has been shown that during their expansion Africanized honeybees have low levels of introgressed alleles from resident European populations. In the United States, it has been speculated, but not shown, that Africanized honeybees would hybridize extensively with European ho...

'We are doing our best': African and African-Caribbean fatherhood, health and preventive primary care services, in England.

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Williams, Robert; Hewison, Alistair; Stewart, Mel; Liles, Clive; Wildman, Stuart

2012-03-01

Recent policy pronouncements emphasise the importance of engaging fathers with preventive primary care services. However, in England, there is a paucity of literature which examines African and African-Caribbean fathers' experiences of service provision. This paper reports a study that investigated African and African-Caribbean fathers' beliefs about fatherhood, health and preventive primary care services, with the aim of addressing the deficit in the literature. Nine focus groups involving 46 African and African-Caribbean fathers, recruited using purposive sampling, were undertaken between October 2008-January 2009. Fatherhood was seen as a core aspect of the participants' identities. The fathers enacted these identities in a number of ways, such as caring for and protecting children, which were influenced by spirituality, relationships with women, paid work and racism. The fathers had concerns about their bodies, medical conditions, physical activity and forms of consumption. However, their primary focus was on maintaining and improving the well-being of their children. This resulted in them neglecting their own health needs as they had to meet the obligations of family life and paid work. The fathers reported limited contact with preventive primary care services and were unaware of their purpose, function and availability. They identified ethnicity as a positive asset, and felt their families and communities had particular strengths. However they acknowledged that structural constraints, including racism, influenced their perceptions of and access to local health services. The engagement of African and African-Caribbean fathers needs to be addressed more specifically in policy as part of a broader programme of action to tackle health inequalities. In addition, child health services could build on fathers' commitment to children's well-being through practice that addresses fathers' as well as mothers' needs in families. © 2011 Blackwell Publishing Ltd.

Bee Alert: Africanized Honey Bee Facts

OpenAIRE

Lazaneo, Vincent

2002-01-01

Information on how to “bee prepared” for the movement of the Africanized honey bee into California. Includes tips on how to identify Africanized honey bees, bee-proofing your home, and what to do if stung.

African children's literature: a scholar's guide | Osaki | University of ...

African Journals Online (AJOL)

African children's books remain unparalleled in their ability to nurture the imagination and to provide relevant instruction and delight to the African child. Despite this truth, little research has been done on African literature, its nature, form and source of materials. This paper provides a selected check list of words by African ...

Archives: Pan African Medical Journal

African Journals Online (AJOL)

Items 1 - 28 of 28 ... Archives: Pan African Medical Journal. Journal Home > Archives: Pan African Medical Journal. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 28 of 28 Items ...

Archives: African Crop Science Journal

African Journals Online (AJOL)

Items 1 - 50 of 99 ... Archives: African Crop Science Journal. Journal Home > Archives: African Crop Science Journal. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 50 of 99 ...

Archives: African Crop Science Journal

African Journals Online (AJOL)

Items 51 - 99 of 99 ... Archives: African Crop Science Journal. Journal Home > Archives: African Crop Science Journal. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 51 - 99 of 99 ...

African Journal of Political Science

African Journals Online (AJOL)

The AJPS is published by the African Association of Political Science (AAPS), with the aim of providing a platform for African perspectives on issues of politics, economy and society in Africa. It is published 2 times a year - in June and December, and targeted at the social science community, policy-makers, and university ...

Towards an African Philosophy of Education.

Science.gov (United States)

Ocaya-Lakidi, Dent

1980-01-01

Compares and contrasts contemporary philosophies of education in Africa with two philosophical doctrines (naturalism and idealism). Topics discussed include value selectors, westernization, the role of missionaries in African education, critical consciousness, relevance, and African education today. (DB)

Delivering a radiation protection dividend: systemic capacity-building for the radiation safety profession in Africa

Directory of Open Access Journals (Sweden)

Julian Hilton

2014-12-01

Full Text Available Many African countries planning to enter the nuclear energy “family” have little or no experience of meeting associated radiation safety demands, whether operational or regulatory. Uses of radiation in medicine in the continent, whether for diagnostic or clinical purposes, are rapidly growing while the costs of equipment, and hence of access to services, are falling fast. In consequence, many patients and healthcare workers are facing a wide array of unfamiliar challenges, both operational and ethical, without any formal regulatory or professional framework for managing them safely. This, combined with heighted awareness of safety issues post Fukushima, means the already intense pressure on radiation safety professionals in such domains as NORM industries and security threatens to reach breaking point. A systematic competency-based capacity-building programme for RP professionals in Africa is required (Resolution of the Third AFRIRPA13 Regional Conference, Nairobi, September 2010. The goal is to meet recruitment and HR needs in the rapidly emerging radiation safety sector, while also addressing stakeholder concerns in respect of promoting and meeting professional and ethical standards. The desired outcome is an RP “dividend” to society as a whole. A curriculum model is presented, aligned to safety procedures and best practices such as Safety Integrity Level and Layer of Protection analysis; it emphasizes proactive risk communication both with direct and indirect stakeholders; and it outlines disciplinary options and procedures for managers and responsible persons for dealing with unsafe or dangerous behavior at work. This paper reports on progress to date. It presents a five-tier development pathway starting from a generic foundation course, suitable for all RP professionals, accompanied by specialist courses by domain, activity or industry. Delivery options are discussed. Part of the content has already been developed and delivered as

African ancestry protects against Alzheimer's disease-related neuropathology.

Science.gov (United States)

Schlesinger, D; Grinberg, L T; Alba, J G; Naslavsky, M S; Licinio, L; Farfel, J M; Suemoto, C K; de Lucena Ferretti, R E; Leite, R E P; de Andrade, M P; dos Santos, A C F; Brentani, H; Pasqualucci, C A; Nitrini, R; Jacob-Filho, W; Zatz, M

2013-01-01

Previous studies in dementia epidemiology have reported higher Alzheimer's disease rates in African-Americans when compared with White Americans. To determine whether genetically determined African ancestry is associated with neuropathological changes commonly associated with dementia, we analyzed a population-based brain bank in the highly admixed city of São Paulo, Brazil. African ancestry was estimated through the use of previously described ancestry-informative markers. Risk of presence of neuritic plaques, neurofibrillary tangles, small vessel disease, brain infarcts and Lewy bodies in subjects with significant African ancestry versus those without was determined. Results were adjusted for multiple environmental risk factors, demographic variables and apolipoprotein E genotype. African ancestry was inversely correlated with neuritic plaques (P=0.03). Subjects with significant African ancestry (n=112, 55.4%) showed lower prevalence of neuritic plaques in the univariate analysis (odds ratio (OR) 0.72, 95% confidence interval (CI) 0.55-0.95, P=0.01) and when adjusted for age, sex, APOE genotype and environmental risk factors (OR 0.43, 95% CI 0.21-0.89, P=0.02). There were no significant differences for the presence of other neuropathological alterations. We show for the first time, using genetically determined ancestry, that African ancestry may be highly protective of Alzheimer's disease neuropathology, functioning through either genetic variants or unknown environmental factors. Epidemiological studies correlating African-American race/ethnicity with increased Alzheimer's disease rates should not be interpreted as surrogates of genetic ancestry or considered to represent African-derived populations from the developing nations such as Brazil.

The socio-cultural implications of African music and dance ...

African Journals Online (AJOL)

This paper sets out to discuss the socio-cultural implications of African music and dance. To this end, the paper looks at African music, African dance and human culture, kinds of dance, dance and the human body, dance and the society, the interrelationship between African music and dance, the importance of dance to the ...

The African diaspora: history, adaptation and health.

Science.gov (United States)

Rotimi, Charles N; Tekola-Ayele, Fasil; Baker, Jennifer L; Shriner, Daniel

2016-12-01

The trans-Atlantic slave trade brought millions of Africans to the New World. Advances in genomics are providing novel insights into the history and health of Africans and the diasporan populations. Recent examples reviewed here include the unraveling of substantial hunter-gatherer and 'Eurasian' admixtures across sub-Saharan Africa, expanding our understanding of ancestral African genetics; the global ubiquity of mixed ancestry; the revealing of African ancestry in Latin Americans that likely derived from the slave trade; and understanding of the ancestral backgrounds of APOL1 and LPL found to influence kidney disease and lipid levels, respectively, providing specific insights into disease etiology and health disparities. Published by Elsevier Ltd.

Dismantling reified African culture through localised homosexualities in Uganda.

Science.gov (United States)

Nyanzi, Stella

2013-01-01

Uganda's Anti-Homosexuality Bill of 2009 aimed at protecting the cherished culture of the people against emergent threats to the traditional heterosexual family. The Bill's justification, however, lay in myopic imaginings of a homogenous African-ness and pedestrian oblivion to pluralities within African sexualities. This paper revisits the debate that homosexuality is 'un-African'. Rhetoric analysis of the Anti-Homosexuality Bill exposes how dominant discourses of law, medicine, religion, geography and culture reinforce the view that homosexuality is foreign to Africa. Based on ethnography in contemporary Uganda, I explore how self-identified same-sex-loving individuals simultaneously claim their African-ness and their homosexuality. Their strategies include ethnic belonging, membership to kinship structures, making connections with pre-colonial histories of homosexuality, civic participation in democratic processes, national identity, organising of lesbian, gay, bisexual, transgender, intersex and questioning support groups, language and nomenclature, visibility and voice in local communal activities, solidarity and adherence to cultural rituals. In present-day Uganda, same-sex-loving men, women and transgender people variously assert their African-ness.

Afro-Americans and Early Pan-Africanism

Science.gov (United States)

Contee, Clarence G.

1970-01-01

History of the Pan-African movement, the roles of W.E.B.Du Bois and Marcus Garvey in the movement activities, and the shift to African based leadership of the movement in the 1940's are discussed. (KG)

New partnership for African development | CRDI - Centre de ...

International Development Research Centre (IDRC) Digital Library (Canada)

... to promote business relationships between Canadian companies and African partners. ... This affirmation of African leadership marks a dramatic and important ... Unlike previous development plans, NEPAD places an emphasis not on aid but ... most vibrant components of African economic activity operate in the informal ...

Defense.gov Special Report: African American History Month

Science.gov (United States)

in Military and Business Tuskegee Airman Shares History Soldier's Life Provides Example for West Department of Defense Submit Search During National African-American History Month, we celebrate the rich In honor of African-American History Month, Fred Moore, the first African-American Tomb Guard

AIDS Prevention in the Southern African Development Community ...

International Development Research Centre (IDRC) Digital Library (Canada)

AIDS Prevention in the Southern African Development Community : Policy Research and Decision Support. The Southern African Development Community (SADC) is at the epicentre of the AIDS pandemic. The regional adult HIV prevalence is approximately 11%, twice the average in other African countries. Scores of ...

U.S. - African Partnerships: Advancing Common Interests

Science.gov (United States)

2017-12-01

democratic development are still needed. At the same time, some emphasized that while strong leadership is important, strong institutions are even more...Gordon  Illustrations on “ Democratic Trends in Africa” Taking Overall Stock Overall, the day’s proceedings illustrated how far U.S.-African...cooperation. African Democratic Governance: A Mixed Picture Trends in African democratization are somewhat erratic, with examples of both progress and

The African Credit Trap

OpenAIRE

Svetlana Andrianova; Badi H. Baltagi; Panicos O. Demetriades; David Fielding

2010-01-01

We put forward a plausible explanation of African financial underdevelopment in the form of a bad credit market equilibrium. Utilising an appropriately modified IO model of banking, we show that the root of the problem could be unchecked moral hazard (strategic loan defaults) or adverse selection (a lack of good projects). We provide empirical evidence from a large panel of African banks which suggests that loan defaults are a major factor inhibiting bank lending when the quality of regulatio...

Archives: African Journal of Urology

African Journals Online (AJOL)

Items 1 - 50 of 66 ... Archives: African Journal of Urology. Journal Home > Archives: African Journal of Urology. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 50 of 66 Items, 1 2 ...

"Women ... Mourn and Men Carry on": African Women Storying Mourning Practices--A South African Example

Science.gov (United States)

Kotze, Elmarie; Els, Lishje; Rajuili-Masilo, Ntsiki

2012-01-01

African mourning of loss of lives in South Africa has been shaped by discursive practices of both traditional African cultures and the sociopolitical developments under apartheid and in post-apartheid South Africa. This article reports on changes in mourning practices on the basis of a literature review and uses a collection of examples to…

The Patterns of Care Survey of radiation therapy in localized prostate cancer: Similarities between the practice nationally and in minority-rich areas

International Nuclear Information System (INIS)

Zietman, Anthony; Moughan, Jennifer; Owen, Jean; Hanks, Gerald

2001-01-01

Purpose: Over the last two decades, the chance for the cure of localized prostate cancer by radiation has been improved by the widespread use of PSA for early detection and by a number of technical advances in treatment delivery. This study was designed to determine whether the stage of presentation and the quality of radiation treatment delivered are comparable between Caucasian and minority patients nationally and within minority-rich areas. Methods and Materials: A random survey conducted for the Patterns of Care Study in Radiation Oncology of 80 facilities treating patients with radiation in the USA. Of these, 67 comprise the 'National Survey' and 13 a 'Minority-Rich' survey (>40% of treated patients are minorities). Nine hundred twenty-six men with localized prostate cancer were treated in 1994. Five hundred ninety-five were in the national and 331 in the minority-rich survey. The main outcome measures were the clinical features of Caucasian and minority men at presentation and technical characteristics of the treatment delivered to them. Results: African-American men presented with more advanced disease (higher-presenting PSA and T-stage) than Caucasians in both the national and the minority-rich surveys. Hispanics also presented with later disease and could be grouped with African-American men rather than Caucasians. Overall the stage and PSA at presentation was earlier than seen in the previous Patterns of Care Study survey of 1989. The quality of treatment delivered has improved since 1989, with no distinction seen between those facilities sampled nationally and those within minority-rich areas. Conclusion: African-American and Hispanic men with prostate cancer present for therapy at a later stage than Caucasian men, but when they do, the treatment received is of comparable quality

African Languages in a Digital Age

International Development Research Centre (IDRC) Digital Library (Canada)

Aspects of sustainability in the long term, including follow-through and marketing of ...... Translation memory (TM) has had some application for African languages. ... Africans abroad are a key group in the short term, with an actual and potential ...

South African Journal of Cultural History

African Journals Online (AJOL)

South African Journal of Cultural History. ... attempt to change the Afrikaner's views of San rock art · EMAIL FULL TEXT EMAIL FULL TEXT ... Two unknown music fragments in the Grey Collection of the South African Library, Cape Town ...

Simulation of African dust properties and radiative effects during the 2015 SHADOW campaign in Senegal

Science.gov (United States)

Péré, J.-C.; Rivellini, L.; Crumeyrolle, S.; Chiapello, I.; Minvielle, F.; Thieuleux, F.; Choël, M.; Popovici, I.

2018-01-01

The aim of this work is to estimate optical and radiative properties of dust aerosols and their potential feedbacks on atmospheric properties over Western Africa for the period 20 March-28 April 2015, by using numerical simulations and different sets of remote-sensing and in-situ measurements. Comparisons of simulations made by the on-line coupled meteorological-chemistry model WRF-CHEM with MODIS, AERONET and in-situ observations result in a general agreement for the spatio-temporal variations of aerosol extinction at both local and regional scales. Simulated SSA reached elevated values between 0.88 and 0.96 along the visible/near-infrared in close agreement with AERONET inversions, suggesting the predominance of dust over Western Africa during this specific period. This predominance of dust is confirmed by in-situ measurements of the aerosol size distribution, fitting well with the aerosols size distribution simulated by WRF-CHEM. The impact of this large dust load on the radiative fluxes leads to large modifications of the shortwave and longwave radiative budget both at the ground and at the top of the atmosphere. In return, the response of the atmosphere to these dust-induced radiative changes is the alteration of the surface air temperature and wind fields, with non-negligible impact on the dust emission and transport.

Towards an African Peace and Security regime: Continental ...

African Journals Online (AJOL)

The anticipated establishment of an African Standby Force (ASF) in 2015 and the interim African Capacity for Immediate Response to Crises (ACIRC), in the midst of new and continuing conflicts, have sparked renewed interest in the underpinnings of, and prospects for, the African Peace and Security Architecture.

African American Educational Leadership in the School Superintendency

Science.gov (United States)

Smith, Eva C.

2013-01-01

African American educational leadership has long been part of American education and African American activism to resist oppression. However, the field of educational leadership has rarely included the contributions of African American leaders, particularly women leaders, into mainstream leadership theory and practices. This omission is difficult…

Our Continent, Our Future: African Perspectives on Structural ...

International Development Research Centre (IDRC) Digital Library (Canada)

Our Continent, Our Future: African Perspectives on Structural Adjustment ... Our Continent, Our Future presents the emerging African perspective on this complex issue. ... approach to structural adjustment, and it does so with the input and support ... Committee of the Association of African Universities, the International Board ...

Perverse and Necessary Dialogues in African Philosophy1

African Journals Online (AJOL)

Jennifer Vest

African philosophy or African rationality is to engage in perverse and unnecessary .... magical epistemologies, and universality vs. cultural particularity have all been shaped by .... unanimous, and emotional rather than rational. .... message of Christianity” (Mbiti 1969, 13), and trying “to counteract the myths of the African.

African Health Economics and Policy Research Capacity Building ...

International Development Research Centre (IDRC) Digital Library (Canada)

African Health Economics and Policy Research Capacity Building and Dissemination. As African countries move toward universal health coverage, it is clear there is a shortage of African experts with applied research skills in health financing such as fiscal space analysis, needs-based resource allocation methods, and ...

Alternative Concepts and Terminologies for Teaching African Art.

Science.gov (United States)

Chanda, Jacqueline

1992-01-01

Considers concepts and terminologies that focus on generalizations concerning traditional African art and cultures. Argues that alternative concepts and terminologies should be used in developing curriculum and in teaching non-Western art. Discusses traditional African religious beliefs, primitivism, and the function of African art objects. (KM)

The African proverbs project and after | Mbiti | Lexikos

African Journals Online (AJOL)

The Project has generated both local and international interest in African paremiography and paremiology. Four academic institutions in South Africa, Kenya, Ghana and the Ivory Coast, with links to others in Africa, Europe and America, are continuing this work on proverbs. Keywords: african proverbs project, african ...

Developing programs for african families, by african families

DEFF Research Database (Denmark)

Halliday, Jennifer A; Green, Julie; Mellor, David

2013-01-01

Obesity is an emerging problem for African migrants in Australia, but few prevention programs incorporate their cultural beliefs and values. This study reports on the application of community capacity-building and empowerment principles in 4 workshops with Sudanese families in Australia. Workshop...

Clinical utility of the Rorschach with African Americans.

Science.gov (United States)

Presley, G; Smith, C; Hilsenroth, M; Exner, J

2001-12-01

In this study we sought to identify Rorschach differences between African Americans and White Americans and to understand these differences within a social and cultural framework. Data from the Exner (1993) Comprehensive System normative sample (N = 700) was used to form a group of 44 African Americans and 44 White Americans matched for age, sex, education, and socioeconomic status. Twenty-three Rorschach variables were chosen a priori and group differences were analyzed. The only clinically significant difference found was that African Americans offered significantly less cooperative movement. This lower frequency of cooperative movement may suggest African Americans do not anticipate cooperative interactions with others as a routine event. This may reflect a shared feeling among African Americans that most members of our society are less likely to be sensitive to or responsive to their needs relative to others. However, the study demonstrates a striking similarity between the groups, supporting the clinical use of the Rorschach with African Americans.